The List of Studies that Support the Claims that Same Sex Behavior is Natural & Established Prior to Birth.
Current List count: 151, although estimates of studies counts are in the 1000s. Please comment with any I've missed.
Guard Rails:
1) Animal behavior vs. human sexual orientation
Same sex sexual behavior observed in animals is not identical to human sexual orientation. Animal studies provide strong evidence that same-sex sexual behavior is a naturally occurring phenomenon in nature across many species. However, these findings are more limited when it comes to human identity categories such as sexual orientation, which involve additional psychological, social, and developmental dimensions.
2) What human studies actually conclude
Human focused research does not typically conclude in explicit terms that “homosexuality is natural.” Instead, the scientific literature consistently shows that sexual orientation is associated with biological and developmental factors, including genetic influences, prenatal conditions, and neuroanatomical correlates. These findings do not support a simple explanation of sexual orientation as a purely voluntary or conscious choice, but they also do not reduce it to a single cause or mechanism.
There is no strong scientific evidence showing that sexual orientation is determined by specific experiences after birth in a consistent or causal way. While environment and life experiences shape many aspects of human behavior, research has not identified any reliable post birth factors that can predict or produce same sex attraction.
Instead, the evidence that does exist points toward a multifactorial model, where biological and developmental influences, including prenatal factors, play a significant role. These influences are not fully deterministic, but they are consistently supported across multiple lines of research.
Because science cannot isolate a single cause, it does not claim absolute certainty. However, the overall pattern of evidence strongly suggests that sexual orientation is not a simple outcome of conscious choice or post birth experiences.
The List:
1) Bailey, N. W. & Zuk, M. (2009). Same-sex sexual behavior and evolution.
Link: https://pubmed.ncbi.nlm.nih.gov/19539396/
Strongly suggests: Same sex sexual behavior is extensively documented in non-human animals and is a legitimate topic of evolutionary study.
Does not strongly suggest: That all same-sex behavior across species has the same cause, function, or meaning as human sexual orientation.
2) Monk, J. D. et al. (2019). An alternative hypothesis for the evolution of same-sex sexual behaviour in animals.
Link: https://pubmed.ncbi.nlm.nih.gov/31740842/
Strongly suggests: Same sex sexual behavior has been recorded in over 1,500 animal species and is widespread across major clades. It also argues that the behavior need not be treated as an evolutionary anomaly.
Does not strongly suggest: That same-sex sexual behavior is ancestral in every lineage, or that one universal explanation accounts for it in all animals.
3) Gómez, J. M. et al. (2023). The evolution of same-sex sexual behaviour in mammals.
Link: https://www.nature.com/articles/s41467-023-41290-x
Strongly suggests: Same-sex sexual behavior is common enough in mammals to be studied comparatively and appears repeatedly across mammalian evolution rather than as a one-off aberration.
Does not strongly suggest: That same-sex sexual behavior is ancestral to all mammals, or that every observed case reflects stable orientation in a human-like sense.
4) Anderson, K. A. et al. (2024). Same-sex sexual behaviour among mammals is widely underreported.
Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11189198/
Strongly suggests: Same-sex sexual behavior in mammals is not just present but likely undercounted because of observation and reporting bias.
Does not strongly suggest: That underreporting alone tells us the exact prevalence in every species.
5) Cunningham, E. et al. (2024). Reframing mechanistic studies on same-sex sexual behaviours in primates.
Link: https://pubmed.ncbi.nlm.nih.gov/38278061/
Strongly suggests: Same-sex sexual behaviors in primates are real, historically misframed, and worth studying without treating them as pathology by default.
Does not strongly suggest: A single mechanistic explanation for all primate same-sex behavior.
6) Vasey, P. L. et al. (2014). Female homosexual behavior and inter-sexual mate competition in Japanese macaques.
Link: https://pubmed.ncbi.nlm.nih.gov/25242104/
Strongly suggests: In Japanese macaques, female same-sex sexual behavior is sexually motivated and not well explained by the sociosexual hypotheses tested in that species.
Does not strongly suggest: That this one primate model explains all same-sex behavior in primates or humans.
7) Moscovice, L. R. et al. (2019). Sexual interactions among female bonobos are linked to increases in oxytocin.
Link: https://pubmed.ncbi.nlm.nih.gov/31449811/
Strongly suggests: Female same-sex sexual interactions in bonobos are common enough to quantify and are linked with measurable endocrine changes associated with social bonding.
Does not strongly suggest: That oxytocin fully explains bonobo same-sex behavior or maps directly onto human orientation.
8) Yokoyama, T. et al. (2023). Partner choice in genito-genital rubbing among female bonobos.
Link: https://pubmed.ncbi.nlm.nih.gov/36331625/
Strongly suggests: Female bonobo same-sex sexual behavior is structured and involves partner choice, not random activity.
Does not strongly suggest: That this reflects fixed, exclusive sexual orientation in the human sense.
9) Jankowiak, Ł. et al. (2018). Experimentally evoked same-sex sexual behaviour in females of a colonially breeding bird.
Link: https://www.nature.com/articles/s41598-018-20128-3
Strongly suggests: Same-sex pairing in birds can function as a viable social or reproductive strategy under certain conditions.
Does not strongly suggest: That all same-sex behavior is adaptive or must serve a reproductive function to be considered natural.
10) Balthazart, J. (2020). Sexual partner preference in animals and humans.
Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC7484171/
Strongly suggests: Sexual partner preference has biological components and can be studied across species, including humans.
Does not strongly suggest: That exclusive same-sex preference occurs at similar rates across all species.
11) Roselli, C. E. (2020). The Biology of Same-Sex Attraction in Rams.
Link: https://pubmed.ncbi.nlm.nih.gov/32311371/
Strongly suggests: A subset of rams naturally exhibits same-sex partner preference, making it a useful biological model.
Does not strongly suggest: That findings in rams directly explain human sexual orientation.
12) Roselli, C. E. et al. (2004). Sexual partner preference, hypothalamic morphology and aromatase in rams.
Link: https://pubmed.ncbi.nlm.nih.gov/15488542/
Strongly suggests: Same-sex partner preference in rams is associated with measurable neurobiological differences.
Does not strongly suggest: That a single brain mechanism determines sexual preference.
13) Roselli, C. E. et al. (2004). The volume of a sexually dimorphic nucleus in the ovine hypothalamus varies with sexual partner preference.
Link: https://pubmed.ncbi.nlm.nih.gov/14525915/
Strongly suggests: Sexual partner preference correlates with differences in specific brain structures in sheep.
Does not strongly suggest: That this correlation proves causation or fully explains behavior.
14) Roselli, C. E. (2011). The development of male-oriented behavior in rams.
Link: https://pubmed.ncbi.nlm.nih.gov/21215767/
Strongly suggests: Same-sex partner preference in rams develops naturally and can be studied developmentally.
Does not strongly suggest: That prenatal biology alone explains all variation in preference.
15) Ganna, A. et al. (2019). Large-scale GWAS reveals insights into the genetic architecture of same-sex sexual behavior.
Link: https://www.science.org/doi/10.1126/science.aat7693
Alt link: https://pmc.ncbi.nlm.nih.gov/articles/PMC7082777/
Strongly suggests: Same-sex sexual behavior in humans has a genetic component that is complex and polygenic.
Does not strongly suggest: That a single gene determines sexual orientation or that genetics alone explains it.
16) Bailey, J. M., Dunne, M. P. & Martin, N. G. (2000). Genetic and environmental influences on sexual orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/10743878/
Strongly suggests: Sexual orientation shows heritable influence in twin studies.
Does not strongly suggest: That genetics alone determines orientation.
17) Rieger, G., Chivers, M. L. & Bailey, J. M. (2005). Sexual arousal patterns of bisexual men.
Link: https://pubmed.ncbi.nlm.nih.gov/15895612/
Strongly suggests: Sexual orientation is associated with measurable physiological arousal patterns, and these patterns differ in systematic ways between heterosexual, homosexual, and bisexual men.
Does not strongly suggest: That physiological arousal patterns alone fully define sexual orientation, or that they explain the developmental or causal origins of orientation.
18) LeVay, S. (1991). A difference in hypothalamic structure between heterosexual and homosexual men.
Link: https://pubmed.ncbi.nlm.nih.gov/1887219/
Strongly suggests: Sexual orientation may be associated with neuroanatomical differences.
Does not strongly suggest: That these differences cause orientation or fully explain it.
19) Hines, M. (2011). Prenatal endocrine influences on sexual orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/21333673/
Strongly suggests: Prenatal hormonal factors may influence sexual orientation.
Does not strongly suggest: That hormones alone determine orientation.
20) Meyer-Bahlburg, H. F. L. et al. (2008). Sexual orientation in women with congenital adrenal hyperplasia.
Link: https://pubmed.ncbi.nlm.nih.gov/18157628/
Strongly suggests: Prenatal androgen exposure is associated with differences in sexual orientation in some populations.
Does not strongly suggest: That this mechanism explains all cases of homosexuality.
21) Ngun, T. C. & Vilain, E. (2014). The biological basis of human sexual orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/25172350/
Strongly suggests: Sexual orientation has biological underpinnings involving complex interactions of genes and development.
Does not strongly suggest: That a single mechanism fully explains orientation.
22) Bailey, J. M. et al. (2016). Sexual Orientation, Controversy, and Science.
Link: https://pubmed.ncbi.nlm.nih.gov/27113562/
Strongly suggests: Scientific evidence supports biological contributions to sexual orientation and rejects simple “choice-only” explanations.
Does not strongly suggest: That every aspect of sexual orientation is fully understood or resolved.
23) Roselli, C. E. (2009). The neurobiology of sexual partner preferences in rams.
Link: https://pubmed.ncbi.nlm.nih.gov/19446078/
Strongly suggests: A subset of rams naturally shows same-sex partner preference and this preference has identifiable neurobiological correlates.
Does not strongly suggest: That the sheep model alone explains human sexual orientation.
24) Resko, J. A. et al. (1996). Endocrine correlates of partner preference behavior in rams.
Link: https://pubmed.ncbi.nlm.nih.gov/8793066/
Strongly suggests: Male-oriented rams are a real, naturally occurring subgroup that can be studied endocrinologically.
Does not strongly suggest: That endocrine correlates by themselves fully explain partner preference.
25) Stellflug, J. N. et al. (2006). Relationship between sexual behavior classifications of rams and lambing performance of ewes joined in multiple-sire breeding groups.
Link: https://pubmed.ncbi.nlm.nih.gov/16424275/
Strongly suggests: Sexual partner preference testing in rams captures real behavioral variation relevant to breeding behavior.
Does not strongly suggest: That one testing protocol perfectly captures all aspects of ram sexuality.
26) Roselli, C. E. et al. (2009). Prenatal programming of sexual partner preference: the ram model.
Link: https://pubmed.ncbi.nlm.nih.gov/19207819/
Strongly suggests: The ram is a useful developmental model for studying the early programming of same-sex partner preference.
Does not strongly suggest: That prenatal programming is the sole cause of same-sex preference in all species.
27) Roselli, C. E. et al. (2010). The ovine sexually dimorphic nucleus, aromatase, and sexual partner preferences in sheep.
Link: https://pubmed.ncbi.nlm.nih.gov/19883759/
Strongly suggests: Sexual partner preference in sheep is associated with measurable neuroanatomical and enzymatic differences.
Does not strongly suggest: That aromatase alone determines sexual orientation-like outcomes.
28) Perkins, A. et al. (2007). The Ram as a Model for Behavioral Neuroendocrinology.
Link: https://pubmed.ncbi.nlm.nih.gov/17482616/
Strongly suggests: Sheep provide a valid animal model for studying sexual behavior and sexual partner preference.
Does not strongly suggest: That results from sheep map directly and cleanly onto humans.
29) Vasey, P. L. et al. (2002). Sexual partner preference in female Japanese macaques.
Link: https://pubmed.ncbi.nlm.nih.gov/11910792/
Strongly suggests: Female same-sex sexual behavior in Japanese macaques is sexual behavior, not merely nonsexual affiliation.
Does not strongly suggest: That macaque same-sex behavior is identical to human lesbian identity.
30) Vasey, P. L. et al. (2008). Courtship behaviour in Japanese macaques during homosexual consortships.
Link: https://pubmed.ncbi.nlm.nih.gov/18355986/
Strongly suggests: Female Japanese macaques display structured courtship behavior in same-sex consortships.
Does not strongly suggest: That one population or species explains all primate same-sex behavior.
31) O'Neill, A. C. et al. (2004). Ovarian cycle phase and same-sex mating behavior in Japanese macaque females.
Link: https://pubmed.ncbi.nlm.nih.gov/15152371/
Strongly suggests: Same-sex mating in female Japanese macaques varies with reproductive cycle phase, which supports its sexual rather than purely social character.
Does not strongly suggest: That cycle effects explain the entire phenomenon.
32) Vasey, P. L. et al. (2006). Sexual reward via vulvar, perineal, and anal stimulation in female Japanese macaques.
Link: https://pubmed.ncbi.nlm.nih.gov/17048107/
Strongly suggests: Same-sex mounting in female Japanese macaques involves patterned sexual stimulation and likely sexual reward.
Does not strongly suggest: That reward mechanisms are the only reason the behavior persists.
33) Vasey, P. L. et al. (2005). A sexually dimorphic hypothalamic nucleus in a macaque species with frequent female-female mounting and same-sex sexual partner preference.
Link: https://pubmed.ncbi.nlm.nih.gov/15639177/
Strongly suggests: Japanese macaques with frequent female same-sex behavior also show neuroanatomical differences worth studying.
Does not strongly suggest: That the identified nucleus alone causes same-sex preference.
34) Böhm, P. M. et al. (2024). Intense body contact increases homosexual pair bond persistence in Japanese macaques.
Link: https://pubmed.ncbi.nlm.nih.gov/38216783/
Strongly suggests: Same-sex pair bonds in Japanese macaques can show relationship dynamics that are stable enough to measure.
Does not strongly suggest: That all same-sex interactions in macaques are pair-bonded or long-term.
35) Vasey, P. L. (2010). The biogeography and evolution of female homosexual behavior in Japanese macaques.
Link: https://pubmed.ncbi.nlm.nih.gov/19688591/
Strongly suggests: Female same-sex sexual behavior in Japanese macaques is distributed in a pattern that invites evolutionary explanation rather than dismissal as anomaly.
Does not strongly suggest: That one adaptive explanation accounts for all populations.
36) Leca, J.-B. et al. (2018). Hormonal contraceptive affects heterosexual but not homosexual proceptivity in free-ranging female Japanese macaques.
Link: https://pubmed.ncbi.nlm.nih.gov/30171829/
Strongly suggests: Same-sex sexual behavior in free-ranging female macaques is robust enough to be behaviorally compared with opposite-sex proceptivity.
Does not strongly suggest: That contraceptive effects settle the causes of homosexual behavior.
37) Woods, V. et al. (2011). Bonobo but not chimpanzee infants use socio-sexual contact to reduce social tension.
Link: https://pubmed.ncbi.nlm.nih.gov/21127940/
Strongly suggests: Bonobos develop same-sex socio-sexual behavior early enough for it to be studied developmentally and socially.
Does not strongly suggest: That tension reduction is the only function of bonobo same-sex behavior.
38) Wrangham, R. W. (1993). The evolution of sexuality in chimpanzees and bonobos.
Link: https://pubmed.ncbi.nlm.nih.gov/24214293/
Strongly suggests: Bonobo sexuality, including same-sex behavior, has social functions that differ in emphasis from chimpanzees.
Does not strongly suggest: That bonobo behavior should be treated as a direct template for human sexuality.
39) Hashimoto, C. et al. (2006). Comparison of behavioral sequence of copulation between chimpanzees and bonobos.
Link: https://pubmed.ncbi.nlm.nih.gov/16167095/
Strongly suggests: Bonobos and chimpanzees differ in sexual behavior patterns in ways consistent with bonobos’ broader use of sexual contact.
Does not strongly suggest: That this paper alone establishes the full evolutionary meaning of same-sex contact.
40) Paoli, T. et al. (2006). Perineal swelling, intermenstrual cycle, and female homosexual interactions in bonobos.
Link: https://pubmed.ncbi.nlm.nih.gov/16534808/
Strongly suggests: Female-female sexual interactions in bonobos are systematic enough to be analyzed against cycle-related variables.
Does not strongly suggest: That swelling phase fully explains bonobo female same-sex behavior.
41) Brooker, J. S. et al. (2025). Bonobos and chimpanzees overlap in sexual behaviour more than traditionally assumed.
Link: https://pubmed.ncbi.nlm.nih.gov/40046659/
Strongly suggests: Same-sex genital contact is not unique to bonobos and may be more widespread across apes than older caricatures implied.
Does not strongly suggest: That bonobos and chimpanzees are behaviorally identical.
42) Kirk, K. M. et al. (2000). Measurement models for sexual orientation in a community twin sample.
Link: https://pubmed.ncbi.nlm.nih.gov/11206089/
Strongly suggests: Multiple dimensions of sexual orientation in a large twin sample support the presence of heritable influences, especially when orientation is measured more carefully than a simple binary.
Does not strongly suggest: That heritability estimates equal determinism.
43) Whitam, F. L. et al. (1993). Homosexual orientation in twins: a report on 61 pairs and three triplet sets.
Link: https://pubmed.ncbi.nlm.nih.gov/8494487/
Strongly suggests: Twin concordance patterns are consistent with biological contribution to sexual orientation.
Does not strongly suggest: That sexual orientation is explained entirely by genes or entirely by shared family environment.
44) Segal, N. L. (2016). Twin Studies of Sexual Orientation: A Historical Biological Perspective.
Link: https://pubmed.ncbi.nlm.nih.gov/27436054/
Strongly suggests: The twin literature as a whole supports biological influence on sexual orientation.
Does not strongly suggest: That twin studies alone resolve mechanism.
45) Blanchard, R. & Bogaert, A. F. (2001). Fraternal birth order and the maternal immune hypothesis of male homosexuality.
Link: https://pubmed.ncbi.nlm.nih.gov/11534970/
Strongly suggests: The older-brother effect in male homosexuality is real enough to motivate a maternal immune explanation.
Does not strongly suggest: That the maternal immune hypothesis has been proven conclusively in every population.
46) Blanchard, R. (2018). Fraternal Birth Order, Family Size, and Male Homosexuality.
Link: https://pubmed.ncbi.nlm.nih.gov/28608293/
Strongly suggests: The fraternal birth order effect remains detectable when family size is handled carefully.
Does not strongly suggest: That birth order explains most cases of male homosexuality.
47) Blanchard, R. (2022). New Data on Birth Order in Homosexual Men and Women.
Link: https://pubmed.ncbi.nlm.nih.gov/35713755/
Strongly suggests: Newer data continue to support a male-specific older-brother effect.
Does not strongly suggest: That the same pattern applies equally to women.
48) Blanchard, R. & Bogaert, A. F. (1998). The relation of birth order to sexual orientation in men and women.
Link: https://pubmed.ncbi.nlm.nih.gov/9818557/
Strongly suggests: Male homosexuality is associated with having more older brothers.
Does not strongly suggest: That simple birth order, apart from sibling sex composition, explains the effect.
49) Blanchard, R. et al. (2007). Birth order, sibling sex ratio, handedness, and sexual orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/17345165/
Strongly suggests: The older-brother effect can be studied alongside other developmental markers such as handedness.
Does not strongly suggest: That handedness and fraternal birth order operate through one single pathway.
50) Bogaert, A. F. (2007). Interaction of birth order, handedness, and sexual orientation in men.
Link: https://pubmed.ncbi.nlm.nih.gov/17907817/
Strongly suggests: Handedness may moderate the birth-order relationship with male sexual orientation.
Does not strongly suggest: That handedness itself is a direct cause of homosexuality.
51) Bogaert, A. F. (2007). Extreme right-handedness, older brothers, and sexual orientation in men.
Link: https://pubmed.ncbi.nlm.nih.gov/17201537/
Strongly suggests: Developmental markers like handedness may interact with the older-brother effect rather than replace it.
Does not strongly suggest: That handedness is a reliable predictor at the individual level.
52) Kishida, M. & Rahman, Q. (2015). Fraternal Birth Order and Extreme Right-Handedness as Interacting Predictors of Male Sexual Orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/25663238/
Strongly suggests: The older-brother effect and handedness may jointly contribute to variation in male sexual orientation.
Does not strongly suggest: That these two factors explain sexual orientation broadly or completely.
53) Fořt, J. et al. (2024). Examining the Fraternal Birth Order Effect and Sexual Orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/38869747/
Strongly suggests: The fraternal birth order effect is still an active empirical topic and remains testable in modern samples.
Does not strongly suggest: That every new sample will yield equally strong results.
54) Bartlett, N. T. et al. (2024). Does the Fraternal Birth Order Effect Influence Handedness?
Link: https://pubmed.ncbi.nlm.nih.gov/37415027/
Strongly suggests: Researchers are now testing whether the older-brother effect relates to other developmental markers rather than treating it as an isolated fact.
Does not strongly suggest: That the linkage to handedness is firmly established.
55) Blanchard, R. (1997). H-Y antigen and homosexuality in men.
Link: https://pubmed.ncbi.nlm.nih.gov/9156085/
Strongly suggests: The older-brother effect motivated immunological models early on and was considered strong enough to warrant mechanistic explanation.
Does not strongly suggest: That H-Y antigen findings proved the mechanism by themselves.
56) Bogaert, A. F. & Skorska, M. N. (2011). Sexual orientation, fraternal birth order, and the maternal immune hypothesis.
Link: https://pubmed.ncbi.nlm.nih.gov/21315103/
Strongly suggests: The maternal immune hypothesis has accumulated enough evidence to serve as a serious explanatory framework for the older-brother effect.
Does not strongly suggest: That maternal immune processes explain female sexual orientation or all male cases.
57) Balthazart, J. (2011). Minireview: Hormones and human sexual orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/21693676/
Strongly suggests: Hormonal and developmental biology are relevant to human sexual orientation.
Does not strongly suggest: That hormones provide a single, sufficient explanation.
58) Mustanski, B. S. et al. (2002). A critical review of recent biological research on human sexual orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/12836730/
Strongly suggests: By the early 2000s, there was already a substantial biological literature on sexual orientation worth synthesizing critically.
Does not strongly suggest: That every reported biological correlate was equally robust.
59) McFadden, D. & Pasanen, E. G. (1999). Spontaneous otoacoustic emissions in heterosexuals, homosexuals, and bisexuals.
Link: https://pubmed.ncbi.nlm.nih.gov/10212421/
Strongly suggests: Auditory-system measures differ on average by sexual orientation in ways consistent with developmental biological influences, especially in women.
Does not strongly suggest: That otoacoustic emissions are a direct test of orientation.
60) McFadden, D. & Pasanen, E. G. (1998). Comparison of the auditory systems of heterosexuals and homosexuals.
Link: https://pubmed.ncbi.nlm.nih.gov/9482952/
Strongly suggests: Some auditory traits show average group differences associated with sexual orientation.
Does not strongly suggest: That these differences are large enough for individual diagnosis or that they prove a single prenatal-hormone account.
61) McFadden, D. & Champlin, C. A. (2000). Comparison of auditory evoked potentials in heterosexual, homosexual, and bisexual males and females.
Link: https://pubmed.ncbi.nlm.nih.gov/11548240/
Strongly suggests: Auditory evoked potentials also show orientation-related group differences in some measures.
Does not strongly suggest: That all auditory findings point in one simple direction across sexes.
62) Loehlin, J. C. & McFadden, D. (2003). Otoacoustic emissions, auditory evoked potentials, and traits related to sexual orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/12710826/
Strongly suggests: Several developmental and physiological markers can be analyzed together in relation to sexual orientation.
Does not strongly suggest: That the combined marker set yields a single coherent mechanistic explanation.
63) McFadden, D. (2002). Masculinization effects in the auditory system.
Link: https://pubmed.ncbi.nlm.nih.gov/11910797/
Strongly suggests: Some auditory findings are consistent with the hypothesis that atypical androgen exposure may be relevant to sexual orientation-related traits.
Does not strongly suggest: That the prenatal-androgen account has been decisively proven by auditory data alone.
64) Yule, M. A. et al. (2014). Handedness, birth order, and finger length ratios in self-identified sexual orientation groups.
Link: https://pubmed.ncbi.nlm.nih.gov/24045903/
Strongly suggests: Multiple early neurodevelopmental markers can show average associations with sexual orientation.
Does not strongly suggest: That those markers are individually strong or universally replicated.
65) Grimbos, T. et al. (2010). Sexual orientation and the second to fourth finger length ratio: a meta-analysis.
Link: https://pubmed.ncbi.nlm.nih.gov/20364887/
Strongly suggests: Across many samples, lesbians show on average a more male-typical 2D:4D ratio than straight women.
Does not strongly suggest: A strong or consistent comparable effect in men.
66) Swift-Gallant, A. et al. (2022). Evidence for Perinatal Steroid Influence on Human Sexual Orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/34872968/
Strongly suggests: The overall pattern of evidence remains consistent with some role for perinatal steroid influences on sexual orientation.
Does not strongly suggest: That steroid influence is large, uniform, or singular in mechanism.
67) Lippa, R. A. (2003). Are 2D:4D finger-length ratios related to sexual orientation?
Link: https://pubmed.ncbi.nlm.nih.gov/12872893/
Strongly suggests: Digit-ratio findings are mixed and require caution, especially when sample composition is handled carefully.
Does not strongly suggest: That 2D:4D is a universally reliable marker of sexual orientation.
68) Brown, W. M. et al. (2002). Differences in finger length ratios between self-identified homosexual and heterosexual men and women.
Link: https://pubmed.ncbi.nlm.nih.gov/11910785/
Strongly suggests: Some lesbian subgroups show more male-typical digit ratios on average.
Does not strongly suggest: That digit ratio neatly maps all categories of sexual orientation.
69) Kraemer, B. et al. (2006). Finger length ratio (2D:4D) and dimensions of sexual orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/16874008/
Strongly suggests: In women, more homosexual orientation on a continuum can correlate with more male-typical digit ratios.
Does not strongly suggest: A similarly strong effect in men.
70) Watts, T. M. et al. (2018). Finger Length Ratios of Identical Twins with Discordant Sexual Orientations.
Link: https://pubmed.ncbi.nlm.nih.gov/29978344/
Strongly suggests: Within genetically identical female twin pairs, digit ratios can still differ with sexual orientation, which is consistent with prenatal or developmental influences beyond DNA sequence alone.
Does not strongly suggest: That digit ratio is causal or that the same pattern will generalize strongly to males.
71) Zucker, K. J. et al. (1996). Psychosexual development of women with congenital adrenal hyperplasia.
Link: https://pubmed.ncbi.nlm.nih.gov/9047259/
Strongly suggests: Females with CAH show shifts in psychosexual development that are relevant to later sexual orientation.
Does not strongly suggest: That CAH effects are a general explanation for homosexuality in the population at large.
72) Frisén, L. et al. (2009). Gender role behavior, sexuality, and psychosocial adaptation in women with congenital adrenal hyperplasia.
Link: https://pubmed.ncbi.nlm.nih.gov/19567521/
Strongly suggests: Non-heterosexual orientation is more common in women with CAH than in controls, especially in some genotypic groups.
Does not strongly suggest: That prenatal androgen exposure mechanically determines adult orientation.
73) Daae, E. et al. (2020). Sexual Orientation in Individuals With Congenital Adrenal Hyperplasia: A Systematic Review.
Link: https://pubmed.ncbi.nlm.nih.gov/32231525/
Strongly suggests: Across CAH studies, females assigned female at birth show elevated rates of non-heterosexual orientation relative to controls.
Does not strongly suggest: That CAH research yields a single precise effect size applicable to all patients or all contexts.
74) Gondim, R. et al. (2018). Sexual orientation of 46,XX patients with congenital adrenal hyperplasia.
Link: https://pubmed.ncbi.nlm.nih.gov/30322770/
Strongly suggests: In this CAH sample, homosexuality and bisexuality were more prevalent than in the general population.
Does not strongly suggest: That CAH women are predominantly non-heterosexual.
75) Segev-Becker, A. et al. (2020). Women with nonclassic congenital adrenal hyperplasia.
Link: https://pubmed.ncbi.nlm.nih.gov/31968200/
Strongly suggests: Even nonclassic CAH may be associated with subtle shifts in gendered behavior and sexual orientation-related outcomes.
Does not strongly suggest: That the effects are large or clinically uniform.
76) Schernthaner-Reiter, M. H. et al. (2019). Influence of Genotype and Hyperandrogenism on Sexual Function, Gender Identity, and Partner Preference in Women with CAH.
Link: https://pubmed.ncbi.nlm.nih.gov/31447379/
Strongly suggests: Genotype and androgen-related variables in CAH are relevant to partner preference and related psychosexual outcomes.
Does not strongly suggest: That genotype alone predicts sexual orientation.
77) Savic, I. & Lindström, P. (2008). PET and MRI show differences in cerebral asymmetry and functional connectivity between homo- and heterosexual subjects.
Link: https://pubmed.ncbi.nlm.nih.gov/18559854/
Strongly suggests: Brain organization differs on average between homosexual and heterosexual participants in some measurable ways.
Does not strongly suggest: That these differences establish causation or a single brain-based theory of orientation.
78) Savic, I. & Berglund, H. (2005). Brain response to putative pheromones in homosexual men.
Link: https://pubmed.ncbi.nlm.nih.gov/15883379/
Strongly suggests: Brain responses to candidate chemosensory stimuli differ by sexual orientation.
Does not strongly suggest: That pheromone response is the core cause of male homosexuality.
79) Ponseti, J. et al. (2007). Homosexual women have less grey matter in perirhinal cortex and ventral cerebellum than heterosexual women.
Link: https://pubmed.ncbi.nlm.nih.gov/17712410/
Strongly suggests: Some structural brain differences are detectable between lesbian and heterosexual women at the group level.
Does not strongly suggest: That the reported gray-matter differences explain lesbian orientation in any complete sense.
80) Skorska, M. N. et al. (2015). Facial Structure Predicts Sexual Orientation in Both Men and Women.
Link: https://pubmed.ncbi.nlm.nih.gov/25550146/
Strongly suggests: Facial structure contains average morphological information associated with sexual orientation.
Does not strongly suggest: That facial structure can identify orientation with high certainty in individuals.
81) Valentova, J. V. et al. (2014). Shape differences between the faces of homosexual and heterosexual men.
Link: https://pubmed.ncbi.nlm.nih.gov/24132775/
Strongly suggests: Gay and straight male faces can differ on average in measurable shape features.
Does not strongly suggest: That facial morphology determines or fully reflects orientation.
82) González-Álvarez, J. et al. (2017). Perception of Sexual Orientation from Facial Structure.
Link: https://pubmed.ncbi.nlm.nih.gov/28155008/
Strongly suggests: Some facial cues linked to sexual orientation are perceptually meaningful enough to be studied experimentally.
Does not strongly suggest: That people can infer sexual orientation from faces accurately enough for practical classification.
83) Freeman, J. B. et al. (2010). Sexual orientation perception involves gendered facial cues.
Link: https://pubmed.ncbi.nlm.nih.gov/20682754/
Strongly suggests: Observers use gendered facial cues in judging sexual orientation.
Does not strongly suggest: That such judgments are unbiased, precise, or a direct window into biology.
84) Skorska, M. N. et al. (2021). An anthropometric study of sexual orientation and gender expression.
Link: https://pubmed.ncbi.nlm.nih.gov/34531440/
Strongly suggests: A range of body measures can be studied as average correlates of sexual orientation and gender expression.
Does not strongly suggest: That anthropometrics provide a single coherent or diagnostic signature.
85) Fox, E. A. (2001). Homosexual behavior in wild Sumatran orangutans (Pongo pygmaeus abelii).
Link: https://pubmed.ncbi.nlm.nih.gov/11746281/
Strongly suggests: Same-sex sexual behavior is part of the natural behavioral repertoire of at least some wild orangutans, not just captive animals.
Does not strongly suggest: That orangutan same-sex behavior is directly comparable to human sexual orientation categories.
86) Vasey, P. L. (2002). Same-Sex Sexual Partner Preference in Hormonally and Neurologically Unmanipulated Animals.
Link: https://pubmed.ncbi.nlm.nih.gov/12836731/
Strongly suggests: Same-sex sexual partner preference has been documented in some unmanipulated animals, which supports the claim that it can occur naturally rather than only after experimental intervention.
Does not strongly suggest: That such preferences are common across all species or explained by one mechanism.
87) Wallen, K. (1997). Sexual behavior in same-sexed nonhuman primates: is it relevant to understanding human homosexuality?
Link: https://pubmed.ncbi.nlm.nih.gov/10051894/
Strongly suggests: Same-sex sexual behavior in nonhuman primates is common enough and diverse enough to warrant systematic scientific comparison.
Does not strongly suggest: That primate same-sex behavior maps neatly onto human homosexuality.
88) Leca, J.-B. et al. (2014). Male homosexual behavior in a free-ranging all-male group of Japanese macaques.
Link: https://pubmed.ncbi.nlm.nih.gov/24867180/
Strongly suggests: Same-sex consortships and courtship behaviors occur in free-ranging male Japanese macaques under natural social conditions.
Does not strongly suggest: That these behaviors prove exclusive or lifelong orientation in a human sense.
89) Delval, I. et al. (2023). Homosexual Courtship in Young Wild Capuchin Monkeys.
Link: https://pubmed.ncbi.nlm.nih.gov/37286765/
Strongly suggests: Same-sex courtship behavior occurs in wild capuchins and is part of their flexible sociosexual repertoire.
Does not strongly suggest: That one proposed social function fully explains the behavior.
90) Rind, B. et al. (2024). Same-Sex Sexual Behavior, Age-Class, and Coalitions in Male Rhesus Macaques.
Link: https://pubmed.ncbi.nlm.nih.gov/39227500/
Strongly suggests: Same-sex sexual behavior in male rhesus macaques can be analyzed in relation to age class and coalition behavior, which supports its relevance to natural social dynamics.
Does not strongly suggest: That coalition-building is the sole explanation for same-sex behavior in rhesus macaques.
91) Coxshall, C. et al. (2024). Ecological and social pressures drive same-sex sexual behaviour in mammals.
Link: https://pubmed.ncbi.nlm.nih.gov/41526663/
Strongly suggests: Same-sex sexual behavior in mammals can be investigated as an outcome shaped by ecological and social pressures rather than as a mere anomaly.
Does not strongly suggest: That one ecological model explains all mammalian same-sex sexual behavior.
92) Gadpaille, W. J. (1980). Cross-species and cross-cultural contributions to homosexuality research.
Link: https://pubmed.ncbi.nlm.nih.gov/7362422/
Strongly suggests: Same-sex sexual activity had already been recognized decades ago as widespread across many studied mammals and primates.
Does not strongly suggest: That the older comparative literature settles modern questions about mechanism.
93) Hu, S. H. et al. (2008). Patterns of brain activation during visually evoked sexual arousal differ between homosexual and heterosexual men.
Link: https://pubmed.ncbi.nlm.nih.gov/18768725/
Strongly suggests: Sexual orientation is associated with measurable differences in neural activation patterns during sexual arousal.
Does not strongly suggest: That these neural differences by themselves establish the cause of orientation.
94) Safron, A. et al. (2007). Neural correlates of sexual arousal in homosexual and heterosexual men.
Link: https://pubmed.ncbi.nlm.nih.gov/17469913/
Strongly suggests: Homosexual and heterosexual men show category-specific brain activity that aligns with reported erotic preference.
Does not strongly suggest: That a single brain region explains sexual orientation.
95) Sylva, D. et al. (2013). Neural correlates of sexual arousal in heterosexual and homosexual women and men.
Link: https://pubmed.ncbi.nlm.nih.gov/23958585/
Strongly suggests: Neural responses to erotic stimuli differ by sexual orientation and also show sex differences in how differentiated those responses are.
Does not strongly suggest: That neural response profiles are simple or uniform across all individuals.
96) Safron, A. et al. (2018). Neural Correlates of Sexual Orientation in Heterosexual, Bisexual, and Homosexual Women.
Link: https://pubmed.ncbi.nlm.nih.gov/29330483/
Strongly suggests: Homosexual women show subjective and neural response patterns more biased toward female stimuli than heterosexual or bisexual women.
Does not strongly suggest: That bisexuality and homosexuality can be reduced to one linear continuum of brain response.
97) Savic, I. (2010). Sexual differentiation of the human brain in relation to sexual orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/21094885/
Strongly suggests: A body of neuroimaging studies supports the idea that sexual orientation is associated with sex-atypical or cross-sex-shifted features in some brain measures.
Does not strongly suggest: That the brain evidence yields a complete, settled theory of sexual orientation.
98) Abé, C. et al. (2014). Sexual orientation related differences in cortical thickness in male individuals.
Link: https://pubmed.ncbi.nlm.nih.gov/25479554/
Strongly suggests: Sexual orientation is associated with measurable differences in cortical thickness in at least some neuroimaging samples.
Does not strongly suggest: That cortical thickness differences are large, universal, or diagnostic at the individual level.
99) Hu, S. et al. (2014). Differing Default Mode Network Activities in Men With Different Sexual Orientations.
Link: https://pubmed.ncbi.nlm.nih.gov/25099162/
Strongly suggests: Sexual orientation is associated with differences in resting-state brain network activity, not only task-based responses.
Does not strongly suggest: That default mode network differences are specific to sexual orientation alone.
100) Votinov, M. et al. (2021). Brain structure changes associated with sexual orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/33658542/
Strongly suggests: Sexual orientation is reflected in brain-structure characteristics and that these patterns differ by sex.
Does not strongly suggest: That brain-structure associations by themselves establish causation.
101) Abé, C. et al. (2021). Cross-sex shifts in two brain imaging phenotypes and their relation to sexual orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/33635603/
Strongly suggests: Some brain-imaging phenotypes associated with sexual orientation fit a cross-sex-shift pattern.
Does not strongly suggest: That all brain findings related to sexual orientation follow a cross-sex-shift model.
102) Burke, S. M. et al. (2017). Structural connections in the brain in relation to gender identity and sexual orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/29263327/
Strongly suggests: Sexual orientation can be studied in relation to structural brain connectivity, and such variation fits within a biological framework.
Does not strongly suggest: That the same neural patterns underlie sexual orientation and gender identity.
103) Savic, I. & Berglund, H. (2005). Brain response to putative pheromones in homosexual men.
Link: https://pubmed.ncbi.nlm.nih.gov/15883379/
Strongly suggests: Homosexual men show chemosensory brain-response patterns that differ from heterosexual men in ways relevant to sexual preference.
Does not strongly suggest: That pheromone-like responses are the main driver of sexual orientation.
104) Rahman, Q. & Wilson, G. D. (2005). The neurodevelopment of human sexual orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/16143171/
Strongly suggests: A broad range of evidence is consistent with the view that sexual orientation is laid down, at least in part, during early neurodevelopment.
Does not strongly suggest: That early fetal development explains all aspects of human sexual orientation.
105) Roselli, C. E. (2018). Neurobiology of gender identity and sexual orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/29211317/
Strongly suggests: Prenatal developmental factors acting on the brain are relevant to sexual orientation.
Does not strongly suggest: That the same evidence supports identical conclusions for every sex, orientation, or identity category.
106) Gooren, L. (2006). The biology of human psychosexual differentiation.
Link: https://pubmed.ncbi.nlm.nih.gov/16870186/
Strongly suggests: Prenatal androgenization studies, especially in 46,XX individuals, support a biological role in later psychosexual development.
Does not strongly suggest: That psychosexual differentiation can be reduced to hormones alone.
107) Meyer-Bahlburg, H. F. L. (1979). Sex hormones and female homosexuality: a critical examination.
Link: https://pubmed.ncbi.nlm.nih.gov/475573/
Strongly suggests: Researchers were investigating biological and hormonal correlates of female homosexuality decades ago, and the literature was already substantial enough to warrant critical review.
Does not strongly suggest: That adult circulating hormone levels provide a simple explanation for female homosexuality.
108) Mustanski, B. et al. (2017). Sexual orientation and neurocognitive ability: A meta-analysis.
Link: https://pubmed.ncbi.nlm.nih.gov/28698022/
Strongly suggests: Sexual orientation is associated with average differences in some neurocognitive traits that align with the cross-sex-shift hypothesis, especially in homosexual men.
Does not strongly suggest: That cognitive profiles can reliably classify individuals by sexual orientation.
109) Curry, B. B. et al. (2001). Animal models used in identifying gender-related differences.
Link: https://pubmed.ncbi.nlm.nih.gov/11488557/
Strongly suggests: A wide range of animal models, including primates and other vertebrates, can be used to study sex-related behavioral differences relevant to sexual behavior research.
Does not strongly suggest: That all listed animal models directly demonstrate naturally occurring same-sex preference.
110) Kagerer, S. et al. (2011). Neural activation toward erotic stimuli in homosexual and heterosexual men and women.
Link: https://pubmed.ncbi.nlm.nih.gov/21883951/
Strongly suggests: Erotic stimuli activate a widespread neural network, with partly distinct structures underlying sexual preference across homosexual and heterosexual participants.
Does not strongly suggest: That neural activation patterns alone can explain the origin of orientation.
111) Rahman, Q., Wilson, G. D., & Abrahams, S. (2003). Sex, sexual orientation, and identification of positive and negative facial affect.
Link: https://pubmed.ncbi.nlm.nih.gov/14594733/
Strongly suggests: Sexual orientation is associated with differences in certain cognitive and perceptual traits, such as how individuals process emotional facial expressions, which is consistent with broader neurodevelopmental differences.
Does not strongly suggest: That cognitive or perceptual differences cause sexual orientation, or that such differences are large, universal, or sufficient to define orientation.
112) Bailey, J. M. & Pillard, R. C. (1991). A genetic study of male sexual orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/1845227/
Strongly suggests: Male sexual orientation shows familial clustering consistent with a heritable component.
Does not strongly suggest: That genetics alone determines male sexual orientation, or that this study identifies a specific causal gene.
113) Byne, W. & Parsons, B. (1993). Human sexual orientation. The biologic theories reappraised.
Link: https://pubmed.ncbi.nlm.nih.gov/8439245/
Strongly suggests: Biological theories of sexual orientation deserve serious evaluation, but claims in this area need careful scrutiny.
Does not strongly suggest: That the biological basis of sexual orientation had already been conclusively established by 1993.
114) McGuire, T. R. (1995). Is homosexuality genetic? A critical review and some suggestions.
Link: https://pubmed.ncbi.nlm.nih.gov/7560918/
Strongly suggests: Early genetic research on sexual orientation was important but methodologically limited.
Does not strongly suggest: That the absence of definitive proof in older studies means sexual orientation lacks any biological basis.
115) Van Wyk, P. H. & Geist, C. S. (1995). Biology of bisexuality: critique and observations.
Link: https://pubmed.ncbi.nlm.nih.gov/7560936/
Strongly suggests: Bisexuality should be studied directly rather than simply merged with heterosexual or homosexual categories.
Does not strongly suggest: That bisexuality is fully explained by any one biological account.
116) Adams, H. E., Wright, L. W. Jr., & Lohr, B. A. (1996). Is homophobia associated with homosexual arousal?
Link: https://pubmed.ncbi.nlm.nih.gov/8772014/
Strongly suggests: In this sample, men high in homophobia showed greater penile response to male homosexual stimuli than non-homophobic men.
Does not strongly suggest: That homophobia is generally explained by repressed homosexuality, or that this small study resolves that question.
117) Sell, R. L. (1997). Defining and measuring sexual orientation: a review.
Link: https://pubmed.ncbi.nlm.nih.gov/9415799/
Strongly suggests: Sexual orientation is multidimensional and difficult to measure cleanly across identity, behavior, and attraction.
Does not strongly suggest: That one survey question can capture the full construct of sexual orientation.
118) Lalumière, M. L., Blanchard, R., & Zucker, K. J. (2000). Sexual orientation and handedness in men and women: a meta-analysis.
Link: https://pubmed.ncbi.nlm.nih.gov/10900997/
Strongly suggests: Non-right-handedness is modestly more common among homosexual participants, which is consistent with an early neurodevelopmental contribution.
Does not strongly suggest: That handedness is a strong predictor of sexual orientation in individuals.
119) Bem, D. J. (2000). Exotic becomes erotic: interpreting the biological correlates of sexual orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/11100261/
Strongly suggests: Childhood gender nonconformity may be important for understanding later sexual orientation.
Does not strongly suggest: That Bem’s proposed model is established fact rather than an interpretive framework.
120) Chivers, M. L., Rieger, G., Latty, E., & Bailey, J. M. (2004). A sex difference in the specificity of sexual arousal.
Link: https://pubmed.ncbi.nlm.nih.gov/15482445/
Strongly suggests: Men show more category-specific genital arousal patterns than women, and those patterns track sexual orientation more closely.
Does not strongly suggest: That women lack a sexual orientation, or that genital response alone fully defines orientation.
121) Blanchard, R. (2004). Quantitative and theoretical analyses of the relation between older brothers and homosexuality in men.
Link: https://pubmed.ncbi.nlm.nih.gov/15302549/
Strongly suggests: The older-brother effect in male homosexuality is robust enough to support quantitative and theoretical modeling.
Does not strongly suggest: That birth order explains most cases of male homosexuality.
122) Rieger, G., Chivers, M. L., & Bailey, J. M. (2005). Sexual arousal patterns of bisexual men.
Link: https://pubmed.ncbi.nlm.nih.gov/16102058/
Strongly suggests: Sexual arousal can be measured physiologically and compared across orientation groups in men.
Does not strongly suggest: That bisexuality is invalid if one study finds less bisexual genital arousal than self-report would imply.
123) Chivers, M. L. et al. (2005). A sex difference in features that elicit genital response.
Link: https://pubmed.ncbi.nlm.nih.gov/16168255/
Strongly suggests: Men’s genital response tends to be more stimulus-specific, whereas women’s is often less narrowly category-bound.
Does not strongly suggest: That sexual orientation is unimportant in women.
124) Lippa, R. A. (2007). The relation between sex drive and sexual attraction to men and women: a cross-national study of heterosexual, bisexual, and homosexual men and women.
Link: https://pubmed.ncbi.nlm.nih.gov/17380375/
Strongly suggests: Sexual attraction patterns vary across heterosexual, bisexual, and homosexual groups and can be studied in large cross-national samples.
Does not strongly suggest: That sex drive itself causes sexual orientation.
125) Chivers, M. L. et al. (2007). Gender and sexual orientation differences in human sexual response.
Link: https://pubmed.ncbi.nlm.nih.gov/18072857/
Strongly suggests: Genital and subjective sexual arousal differ systematically by sex and sexual orientation.
Does not strongly suggest: That these response patterns are identical across all men or all women.
126) Rieger, G. et al. (2012). Sex and sexual orientation differences in pupil dilation patterns to sexual stimuli.
Link: https://pubmed.ncbi.nlm.nih.gov/22870196/
Strongly suggests: Pupil dilation provides another measurable correlate of sexual orientation and sexual interest.
Does not strongly suggest: That pupil dilation is a perfect or definitive test of orientation.
127) MacInnis, C. C. & Hodson, G. (2013). Is homophobia associated with an implicit same-sex attraction?
Link: https://pubmed.ncbi.nlm.nih.gov/22989040/
Strongly suggests: This study did not support the idea that homophobia is best explained by implicit same-sex attraction.
Does not strongly suggest: That prior findings on homophobia and arousal are fully settled one way or the other.
128) Savic, I. (2014). Pheromone Processing in Relation to Sex and Sexual Orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/24830042/
Strongly suggests: Chemosensory processing differs by sex and sexual orientation in some imaging studies.
Does not strongly suggest: That pheromone processing is the central cause of sexual orientation.
129) Rieger, G. et al. (2015). Sexual arousal: the correspondence of eyes and genitals.
Link: https://pubmed.ncbi.nlm.nih.gov/25603717/
Strongly suggests: Eye-tracking and genital measures can converge in ways relevant to sexual interest and orientation.
Does not strongly suggest: That eye gaze alone can substitute for a full understanding of sexual orientation.
130) Chivers, M. L. et al. (2015). Straight but not narrow; Within-gender variation in the intensity of sexual attraction to men and women.
Link: https://pubmed.ncbi.nlm.nih.gov/26629910/
Strongly suggests: Sexual attraction can vary meaningfully even within groups that identify as straight.
Does not strongly suggest: That orientation categories are useless or have no scientific value.
131) Rosenthal, A. M. et al. (2011). Sexual arousal patterns of bisexual men revisited.
Link: https://pubmed.ncbi.nlm.nih.gov/21763395/
Strongly suggests: Bisexual men’s arousal patterns merit further study and are not settled by a single earlier experiment.
Does not strongly suggest: That one revisit fully resolves the broader literature on male bisexual arousal.
132) Jabbour, J. T. et al. (2019/2020). Sexual Attraction to Both Genders in Ambiphilic Men.
Link: https://pubmed.ncbi.nlm.nih.gov/31691075/
Strongly suggests: Some men reporting attraction to both sexes show evidence of bisexual or ambiphilic response patterns.
Does not strongly suggest: That all men who identify as bisexual show the same physiological profile.
133) Schabath, M. B. et al. (2017). Ask and Tell: The Importance of the Collection of Sexual Orientation and Gender Identity Data to Improve the Quality of Cancer Care for Sexual and Gender Minorities.
Link: https://pubmed.ncbi.nlm.nih.gov/28719237/
Strongly suggests: Collecting sexual orientation data in healthcare settings is important for understanding disparities and improving care.
Does not strongly suggest: That data collection alone resolves those disparities.
134) Bjarnadottir, R. I. et al. (2017). Patient perspectives on answering questions about sexual orientation and gender identity.
Link: https://pubmed.ncbi.nlm.nih.gov/27706875/
Strongly suggests: Many patients are willing to answer sexual orientation questions and often view them as important in healthcare.
Does not strongly suggest: That all patients in all contexts will respond the same way.
135) Razzaghy-Azar, M. et al. (2017). Gender Identity in Patients with Congenital Adrenal Hyperplasia.
Link: https://pubmed.ncbi.nlm.nih.gov/29201068/
Strongly suggests: In this CAH sample, gender identity outcomes were influenced by multiple factors, not just diagnosis alone.
Does not strongly suggest: That CAH produces uniform identity or orientation outcomes across patients.
136) Bogaert, A. F. et al. (2018). Male homosexuality and maternal immune responsivity to the Y-linked protein NLGN4Y.
Link: https://pubmed.ncbi.nlm.nih.gov/29229842/
Strongly suggests: The maternal immune hypothesis gained direct support from observed antibody differences related to male sexual orientation.
Does not strongly suggest: That this mechanism explains all gay men or all variation in male sexual orientation.
137) Apóstolos, R. A. C. et al. (2018). Gender Identity and Sexual Function in 46,XX Patients with Congenital Adrenal Hyperplasia Raised as Males.
Link: https://pubmed.ncbi.nlm.nih.gov/30291599/
Strongly suggests: This small CAH case series found stable male identity and attraction to women in patients raised as males.
Does not strongly suggest: That these findings generalize broadly beyond very specific clinical cases.
138) Wang, Y. et al. (2019). The biological basis of sexual orientation: How hormonal, genetic, and environmental factors influence to whom we are sexually attracted.
Link: https://pubmed.ncbi.nlm.nih.gov/31593707/
Strongly suggests: Sexual orientation is best understood as influenced by multiple biological and developmental factors rather than a single cause.
Does not strongly suggest: That the field has resolved the exact weight of each factor.
139) Xu, Y. et al. (2019). Early life conditions and adolescent sexual orientation: A prospective birth cohort study.
Link: https://pubmed.ncbi.nlm.nih.gov/30762413/
Strongly suggests: Childhood gender nonconformity was strongly associated with later nonheterosexuality in this cohort.
Does not strongly suggest: That childhood gender nonconformity alone determines later sexual orientation.
140) Jabbour, J. T. et al. (2020). Sexual Arousal Patterns of Mostly Heterosexual Men.
Link: https://pubmed.ncbi.nlm.nih.gov/32356085/
Strongly suggests: “Mostly heterosexual” men can show distinct arousal patterns that differ from completely heterosexual men.
Does not strongly suggest: That male sexual orientation is either perfectly continuous or perfectly categorical in every respect.
141) Bogaert, A. F. (2020). A short review of biological research on the development of sexual orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/31911036/
Strongly suggests: The cumulative literature supports biological mechanisms in the development of sexual orientation.
Does not strongly suggest: That any one mechanism is sufficient by itself.
142) Frigerio, A. et al. (2021). A Systematic Review of the Human Neuroimaging Literature on Sexual Orientation.
Link: https://pubmed.ncbi.nlm.nih.gov/33956296/
Strongly suggests: Human neuroimaging studies do show some average differences associated with sexual orientation.
Does not strongly suggest: That neuroimaging findings are uniform, large, or individually diagnostic.
143) Gruia, D. C. et al. (2023). Stability and Change in Sexual Orientation and Genital Arousal Over a 20-Year Period in Men.
Link: https://pubmed.ncbi.nlm.nih.gov/35412933/
Strongly suggests: Self-reported sexual orientation and physiological arousal can show different degrees of stability over time.
Does not strongly suggest: That orientation is simply chosen or endlessly fluid for most men.
144) Bragazzi, N. L. et al. (2023). Probing the genomic landscape of human sexuality: a critical systematic review of the literature.
Link: https://pubmed.ncbi.nlm.nih.gov/37693319/
Strongly suggests: Genomic research supports a complex, polygenic picture rather than a single-gene account of human sexuality.
Does not strongly suggest: That current genomic evidence can predict individual orientation with high accuracy.
145) Warren, A. S. et al. (2022). Childhood gender-typed behaviour, sexual orientation, and mental health outcomes.
Link: https://pubmed.ncbi.nlm.nih.gov/36151838/
Strongly suggests: Childhood gender-typed behavior and adult sexual orientation can be studied together in relation to later mental health outcomes.
Does not strongly suggest: That mental health outcomes are caused by sexual orientation itself rather than by mediating factors such as stigma or abuse.
146) Suen, L. W. et al. (2022). Do Ask, Tell, and Show: Contextual Factors Affecting Sexual Orientation and Gender Identity Disclosure for Sexual and Gender Minority People.
Link: https://pubmed.ncbi.nlm.nih.gov/35073205/
Strongly suggests: Context strongly affects how people disclose sexual orientation in research and healthcare settings.
Does not strongly suggest: That disclosure rates directly reflect the true underlying prevalence of each identity.
147) Holmes, L. et al. (2021). Sexual Orientation, Sexual Arousal, and Finger Length Ratios in Women.
Link: https://pubmed.ncbi.nlm.nih.gov/34297214/
Strongly suggests: Sexual arousal patterns in women can be studied alongside developmental proxy markers such as finger-length ratios.
Does not strongly suggest: That digit ratio is a strong standalone explanation of women’s sexual orientation.
148) Blanchard, R. (2021). Meta-Analyses of Fraternal and Sororal Birth Order Effects in Homosexual Pedohebephiles and Homosexual Teleiophiles.
Link: https://pubmed.ncbi.nlm.nih.gov/32895872/
Strongly suggests: Meta-analytic evidence continues to support an older-brother effect in male same-sex orientation.
Does not strongly suggest: That older sisters have the same effect, or that birth order explains orientation broadly.
149) Sabuncuoglu, O. (2015). High Rates of Same-Sex Attraction/Gender Nonconformity in the Offspring of Mothers with Thyroid Dysfunction During Pregnancy: Proposal of Prenatal Thyroid Model.
Link: https://pubmed.ncbi.nlm.nih.gov/26605033/
Strongly suggests: The author proposed prenatal thyroid dysfunction as a possible developmental factor worth investigating in sexual orientation research.
Does not strongly suggest: That the prenatal thyroid model has been established as a confirmed explanation.
150) Boladale, M. et al. (2015). Sexual orientation and quality of life among students of Obafemi Awolowo University (OAU), Nigeria.
Link: https://pubmed.ncbi.nlm.nih.gov/26958005/
Strongly suggests: Same-sex attraction and nonheterosexual identities can be documented in student populations in Nigeria, and quality-of-life differences can be measured.
Does not strongly suggest: That the findings from one university sample generalize to all settings.
151) Saewyc, E. M. et al. (2004). Measuring sexual orientation in adolescent health surveys: evaluation of eight school-based surveys.
Link: https://pubmed.ncbi.nlm.nih.gov/15830439/
Strongly suggests: The way sexual orientation is asked about in surveys materially affects what researchers capture.
Does not strongly suggest: That any single adolescent survey item gives a complete or perfectly stable measure of orientation.
What you’re actually looking at on PubMed
When you open a PubMed page, you’re usually seeing:
- Citation info (authors, journal, year)
- Abstract (summary of the study)
- Sometimes full text links (PMC, publisher site)
Important:
- The abstract is a summary, not the full study
- Many conclusions are compressed and cautious
No comments:
Post a Comment