Environment and sexual orientation

The relationship between the environment and sexual orientation is a subject of research. In the study of sexual orientation, some researchers distinguish environmental influences from hormonal influences,[1] while other researchers include biological influences such as prenatal hormones as part of environmental influences.[2]

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Scientists do not know the exact cause of sexual orientation, but they theorize that it is the result of a complex interplay of genetic, hormonal, and environmental influences.[1][3][4] They do not view sexual orientation as a choice.[1][3][5]

Hypotheses for the impact of the post-natal social environment on sexual orientation are weak, especially for males.[6] There is no substantial evidence which suggests parenting or early childhood experiences influence sexual orientation,[7][8] but research has linked childhood gender nonconformity and homosexuality.[9][10]

Sexual orientation compared with sexual orientation identity

Often, sexual orientation and sexual orientation identity are not distinguished, which can impact accurately assessing sexual identity and whether or not sexual orientation is able to change; sexual orientation identity can change throughout an individual's life, and may or may not align with biological sex, sexual behavior or actual sexual orientation.[11][12][13] Sexual orientation is stable and unlikely to change for the vast majority of people, but some research indicates that some people may experience change in their sexual orientation, and this is more likely for women than for men.[14] The American Psychological Association distinguishes between sexual orientation (an innate attraction) and sexual orientation identity (which may change at any point in a person's life).[15] Scientists and mental health professionals generally do not believe that sexual orientation is a choice.[1][5]

The American Psychological Association states that "sexual orientation is not a choice that can be changed at will, and that sexual orientation is most likely the result of a complex interaction of environmental, cognitive and biological factors...is shaped at an early age...[and evidence suggests] biological, including genetic or inborn hormonal factors, play a significant role in a person's sexuality".[3] They say that "sexual orientation identity—not sexual orientation—appears to change via psychotherapy, support groups, and life events".[15] The American Psychiatric Association says that individuals may "become aware at different points in their lives that they are heterosexual, gay, lesbian, or bisexual" and "opposes any psychiatric treatment, such as 'reparative' or 'conversion' therapy, which is based upon the assumption that homosexuality per se is a mental disorder, or based upon a prior assumption that the patient should change his/her homosexual orientation". They do, however, encourage gay affirmative psychotherapy.[16]

Childhood gender nonconformity

Researchers have found childhood gender nonconformity (CGN) to be the largest predictor of homosexuality in adulthood.[9][10][17] Gay men often report being feminine boys, and lesbian women often report being masculine girls. In men, CGN is a strong predictor of sexual orientation in adulthood, but this relationship is not as well understood in women.[18][19][20] Women with CAH reported more male typical play behaviours and showed less heterosexual interest.[21]

Daryl Bem proposed the "exotic becomes erotic" theory (EBE) in 1996. Bem argues that biological factors, such as prenatal hormones, genes and neuroanatomy, predispose children to behave in ways that do not conform to their sex assigned at birth. Gender nonconforming children will often prefer opposite-sex playmates and activities. These become alienated from their same-sex peer group. As children enter adolescence "the exotic becomes erotic" where dissimilar and unfamiliar same-sex peers produces arousal, and the general arousal become eroticized over time.[22] However, two critiques of Bem's theory in the journal Psychological Review concluded that "studies cited by Bem and additional research show that Exotic Becomes Erotic theory is not supported by scientific evidence."[23] Bem was criticized for relying on a non-random sample of gay men from the 1970's and for drawing conclusions that appear to contradict the original data. An "examination of the original data showed virtually all respondents were familiar with children of both sexes", and that only 9% of gay men said that "none or only a few" of their friends were male, and most gay men (74%) reported having "an especially close friend of the same sex" during grade school.[23] It is also noted that "71% of gay men reported feeling different from other boys, but so did 38% of heterosexual men. The difference for gay men is larger, but still indicates that feeling different from same-sex peers was common for heterosexual men." Bem also acknowledged that gay men were more likely to have older brothers (the fraternal birth order effect), which appeared to contradict an unfamiliarity with males. Bem cited cross-cultural studies which also "appear to contradict the EBE theory assertion", such as the Sambia tribe in Papua New Guinea, which ritually enforced homosexual acts among teenagers, yet once these boys reached adulthood, only a small proportion of men continued to engage in homosexual behaviour - similar to levels observed in the United States.[23]

In 2003, Lorene Gottschalk, a self-described radical feminist suggested there may be a reporting bias linking gender nonconformity to homosexuality.[24] Researchers have explored the possibility of bias by comparing childhood home videos with self-reports of gender nonconformity, finding that the presence of gender nonconformity was highly consistent with self-reporting, emerged early and carried into adulthood.[25]

Family influences

General

Researchers have provided evidence that gay men report having had less loving and more rejecting fathers, and closer relationships with their mothers, than non-gay men. Some researchers think this may indicate that childhood family experiences are important determinants to homosexuality,[26] or that parents behave this way in response to gender-variant traits in a child.[27][28] Michael Ruse suggests that both possibilities might be true in different cases.[29]

One study reported that homosexual males reported more positive early relationships with mothers than did homosexual females.[30] A 2000 American twin study showed that familial factors, which may be at least partly genetic, influence (but do not determine) sexual orientation.[31]

Research also indicates that homosexual men have significantly more older male siblings than the homosexual women, who, in turn, have significantly more siblings than heterosexual men.[32] A 2006 Danish study compared people who had a heterosexual marriage versus people who had a same-sex marriage. Heterosexual marriage was significantly linked to having young parents, small age differences between parents, stable parental relationships, large numbers of siblings, and late birth order. Children who experience parental divorce are less likely to marry heterosexually than those growing up in intact families. For men, same-sex marriage was associated with having older mothers, divorced parents, absent fathers, and being the youngest child. For women, maternal death during adolescence and being the only or youngest child or the only girl in the family increased the likelihood of same-sex marriage.[26]

Results from a 2008 twin study were consistent with moderate, primarily genetic, familial effects, and moderate to large effects of the nonshared environment (social and biological) on same-sex sexual behavior; the study concluded that, for same-sex sexual behavior, shared or familial environment plays no role for men and minor role for women.[2] By contrast, in a study doing genetic analysis of 409 pairs of homosexual brothers, including twins, strong evidence was found that some homosexual men are born homosexual. The study, including approximately three times as many people as the previous largest study on this subject, indicates that it is significantly more statistically reliable. It links sexual orientation in men with two regions of the human genome that have been implicated before.[33] Lead author of the study, Alan Sanders, however, states that "complex traits such as sexual orientation depend on multiple factors, both environmental and genetic".[34] A region on the X chromosome called Xq28, was originally identified in 1993 by Dean Hamer of the US National Institutes of Health in Bethesda, Maryland. Another region in the twist of chromosome 8, known as 8q12, was first identified in 2005.[35][36]

No evidence has ever been found linking the gender socialization of parents to the sexual orientation of their children[37] while several twin studies have suggested that almost all of the familial resemblance that is observed for sexual orientation is attributable to genes, not family environment.[37][31]

Fraternal birth order
External video
Dr. Ray Blanchard explains the fraternal birth order effect, YouTube video

According to several studies, each additional older brother increases a man's odds of developing a homosexual orientation by 28–48%. Most researchers attribute this to prenatal environmental factors, such as prenatal hormones.[38][39][40][41] One 2006 study reported no relationship between the strength of the effect and degree of homosexual feelings, and hypothesized that the influence of fraternal birth order was not due to a biological, but a social process.[42] However, a large study found the fraternal birth order is not attributable to a social rearing process, since only biological older brothers, and not nonbiological (adopted) older brothers, predicted men’s sexual orientation, regardless of the amount of time reared with these siblings. These results strongly suggest a prenatal origin to the fraternal birth-order effect.[43]

Sexual orientation of boys who were surgically reassigned female

Between the 1960‘s and 2000, many newborn and infant boys were surgically reassigned as females if they were born with malformed penises, or if they lost their penises in accidents.[6]:72-73 Many surgeons believed such males would be happier being socially and surgically reassigned female. In all seven published cases that have provided sexual orientation information, the subjects grew up to be attracted to females. Six cases were exclusively attracted to females, with one case 'predominantly' attracted to females. In a review article in the journal Psychological Science in the Public Interest, six researchers including J. Michael Bailey state this establishes a strong case that male sexual orientation is partly established before birth:

"This is the result we would expect if male sexual orientation were entirely due to nature, and it is opposite of the result expected if it were due to nurture, in which case we would expect that none of these individuals would be predominantly attracted to women. They show how difficult it is to derail the development of male sexual orientation by psychosocial means."

They further argue that this raises questions about the significance of the social environment on sexual orientation, stating, "If one cannot reliably make a male human become attracted to other males by cutting off his penis in infancy and rearing him as a girl, then what other psychosocial intervention could plausibly have that effect?" It is further stated that neither cloacal exstrophy (resulting in a malformed penis), nor surgical accidents, are associated with abnormalities of prenatal androgens, thus, the brains of these individuals were male-organized at birth. Six of the seven identified as heterosexual males at follow up, despite being surgically altered and reared as females, with researchers adding: "available evidence indicates that in such instances, parents are deeply committed to raising these children as girls and in as gender-typical a manner as possible." Bailey et al. describe the occurrence of these sex reassignments as "the near-perfect quasi-experiment" in measuring the impact of 'nature' versus 'nurture' with regards to male homosexuality.[6]

Urban setting

In 1994, Edward Laumann's study of sexual practices in the United States found that a higher proportion of people in urban and city environments report homosexual orientation than in rural areas. However the authors note this may largely driven by migration, as homosexual people move to urban environments for increased acceptance, and because cities provide visible gay and lesbian communities, especially if they feel constrained by negative sanctions toward open homosexuality in their local social networks of friends and family. The authors also hypothesized that large cities could provide a congenial environment for the development and expression of same-gender interest, not out of deliberate choice, but that the environment provides increased opportunities for, and fewer sanctions against, the expression of same-gender attraction.[44][45] This idea was further elaborated in Laumann's later book, The Sexual Organization of the City, which showed that expression of sexual orientation is contingent on the existence of "sex marketplaces," or venues where people with specific sexual orientations can congregate and meet.[46]

Data scientist Seth Stephens-Davidowitz reported that the actual prevalence of gay men doesn't appear to vary between states in the U.S. because the percentage of Internet porn searches that are for gay male porn are nearly the same in all states, about 5%. On this basis he believes migration model is overstated, and says that in states where there is a social stigma against homosexuality that "many more gay men are in the closet than are out".[47][48]

History of sexual abuse

The American Psychiatric Association states: "...no specific psychosocial or family dynamic cause for homosexuality has been identified, including histories of childhood sexual abuse".[49]

In a 30-year longitudinal study published in the Archives of Sexual Behavior, although the authors found that men with histories of childhood sexual abuse were more likely to report ever having had same-sex sexual partners, they did not find any "significant relationships between childhood physical abuse or neglect and same-sex sexual orientation in adulthood"; neither men nor women with histories of childhood physical abuse, sexual abuse, or neglect reported more same-sex sexual partners in the previous year or same-sex romantic cohabitation compared to men and women without such histories.[50] Authors of the study speculated that "sexual abuse may result in uncertainty regarding sexual orientation and greater experimentation with both same- and opposite-sex relationships", but may not affect ultimate sexual orientation.[50]

A large meta-analysis published in the American Journal of Public Health examined 17 population-based studies and found that sexual minority individuals were, on average, 3.8 times more likely to have reported experiencing childhood sexual abuse (unwanted sexual contact before age 18) than non sexual-minorities.[51] However, authors note that organizations such as the American Academy of Pediatrics state that sexual abuse does not cause individuals to become gay, lesbian, or bisexual. Instead, sexual minority individuals are instead more likely to be targeted for sexual abuse.[51]

The explanations for higher rates of abuse are numerous, but largely have not shown a significant link between sexual orientation and sexual abuse. These include:

  • Research has shown that childhood gender nonconformity (typically feminine behavior in boys, and masculinity in girls) makes pre-homosexual children especially vulnerable to predation. Because pre-homosexual children are to some extent identifiable, they may be especially susceptible to same-sex experiences even at young ages as they may be recognized by older opportunistic individuals, or they may be victimized by others who dislike gender nonconformity.[6]:83 A 2015 study found that gay and straight men who were gender nonconforming as children reported significantly higher rates of childhood sexual abuse than gay and straight men who were typically masculine.[52][53] Another Harvard University study of 9,864 individuals found that childhood gender nonconformity was associated with higher rates of childhood sexual, physical, and psychological abuse.[54] S. Bryn Austin, one of the study's authors, said that gender nonconforming young people were more likely to be targeted both within the family and by people outside the family, and that extra precautions should be taken to protect them.[55]
  • Another explanation for higher rates of sexual abuse is that homosexual teenagers are more likely to have sexual experiences with people from outside their social circle. This is because they are likely to be hiding their sexuality from their peers, and because there may be few other gay people in their peer group or school (or any whom they find sufficiently attractive). In contrast, heterosexual teenagers have a wider pool of potential dating and sexual experiences. This may put homosexual teenagers in riskier situations such as age discrepant sexual activity or relationships.[6]:82
  • Similarly, childhood sexual abuse, when defined as: "sexual experiences with an adult or any other person younger than 18 years when the individual did not want the sexual experience or was too young to know what was happening" are combining a number of different experiences, likely to have different causes and effects. For example: sexual experiences of children too young to have understood what was happening, and the sexual experiences of late adolescents who understood those experiences but did not want them, as well as abusive experiences with the same sex and with the other sex.[6]:83
  • There is also possibility of a systematic reporting bias, whereby heterosexual respondents may underreport sexual abuse or non-heterosexual respondents may overreport sexual abuse.[6]:83
  • Sexual minorities can also be victims of corrective rape (or homophobic rape), a hate crime in which someone is sexually assaulted because of their perceived sexual orientation or gender identity. The common intended consequence of the rape, as seen by the perpetrator, is to turn the victim heterosexual or to enforce conformity with gender stereotypes.[56][57]
  • Studies relying on convenience samples can result in higher rates of abuse, which have limited validity describing rates of abuse in the wider population.[51]

Regarding sexual abuse and male homosexuality, researchers J. Michael Bailey and Drew Bailey say there is "compelling evidence that male sexual orientation is fixed early in development, probably before birth and certainly before childhood adversity could plausibly affect it" and that "previous research is inconsistent with the hypothesis that childhood experiences play a significant causal role in adult sexual orientation, especially in men".[58]

See also

References
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