Environment and sexual orientation

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Environment and sexual orientation is research into possible environmental influences on the development of human sexual orientation. Some researchers distinguish environmental influences from hormonal influences^[1] while others include biological influences such as prenatal hormones as part of environmental influences.^[2]

Research has shown that it is a combination of genetic, hormonal, and environmental influences,.^[3] Research has examined the possible genetic, hormonal, developmental, social, and cultural influences on sexual orientation, but no findings have emerged that permit scientists to conclude that sexual orientation is determined by any particular factor or factors.^[4] Research suggests it is biological in nature, determined by a complex interplay of genetic factors and the early uterine environment. Many think that nature and nurture both play complex roles.^[4]

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.^[2]

Childhood gender non-conformity

Researchers have found childhood gender nonconformity to be the largest predictor of homosexuality in adulthood.^[5][6] Daryl Bem suggests that some children will prefer activities that are typical of the other sex and that this will make a gender-conforming child feel different from opposite-sex children, while gender-nonconforming children will feel different from children of their own sex, which may evoke physiological arousal when the child is near members of the sex which it considers as being "different", which will later be transformed into sexual arousal. Researchers have suggested that this nonconformity may be a result of genetics, prenatal hormones, personality, parental care or other environmental factors. Peter Bearman showed that males with a female twin are twice as likely to report same-sex attractions, unless there was an older brother. He says that his findings support the hypothesis that less gendered socialization in early childhood and preadolescence shapes subsequent same-sex romantic preferences. He suggests that parents of opposite-sex twins are more likely to give them unisex treatment, but that an older brother establishes gendersocializing mechanisms for the younger brother to follow.^[7] The proportion of adolescents reporting same-sex attraction is significantly higher than the proportion reporting same-sex sexual experience.In addition to attraction, opportunity has to present itself. Since opportunity is clearly socially structured,our expectation is that social influences should be stronger for behavior than attraction. He suggests possible socialization experiences might shape desire, but not subsequent adult sexual orientation. It is possible that genetic influence could operate on the pathway from attraction to behavior.

Family influences

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.^[8] Some researchers think this may indicate that childhood family experiences are important determinants to homosexuality,^[9] or that parents behave this way in response to gender-variant traits in a child.^[10][11] Michael Ruse suggests that both possibilities might be true in different cases.^[12]

From their research on 275 men in the Taiwanese military, Shu and Lung concluded that "paternal protection and maternal care were determined to be the main vulnerability factors in the development of homosexual males." Key factors in the development of homosexuals were "paternal attachment, introversion, and neurotic characteristics."^[13] One study reported that homosexual males reported more positive early relationships with mothers than did homosexual females.^[14] A 2000 American twin study showed that familial factors, which may be at least partly genetic, influence sexual orientation.^[15]

Research also indicates that homosexual men have significantly more siblings than the homosexual women, who, in turn, have significantly more siblings than heterosexual men.^[16] 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 sibships, 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.^[9]

Fraternal birth order

Main article: Fraternal birth order and sexual orientation

According to several studies, each 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.^{[17][18][19][20]} McConaghy (2006) found no relationship between the strength of the effect and degree of homosexual feelings, suggesting the influence of fraternal birth order was not due to a biological, but a social process.^[21] From more research, people from different countries have different thoughts about the influence to homosexuality by parents. People from Asia think that parents affect children’s sexual orientation a lot. For example, if a child’s parents are not harmony, the child may be afraid of the marriage between a man and a woman and attempt to avoid getting marriage with a person who has the same sex with him. However, people from North American do not think so. Most of them think that environment factor has little influenced on gay and lesbians sexual orientation. They believe that homosexual are born gay and born lesbian who are caused by homosexual genes. For Asia families, for example, Chinese parents pay too much attention on their children especially after China’s one child policy. Every parent has huge expectation on their children, and this expectation becomes huge burdens for the children. For instants, because of the large population in China, the environment is very competitive. Parents hope their children would not fall behind and have more strength for the future job choices. They overstate the importance of study to their children and make them think study hard is the only way to live for future. In this long-term intensive environment, the pressure will lead children stress out and want to escape. From their point of view, study abroad is not only a way to gain more things that they cannot get in their home countries, as well as a way for relaxing.

City of origin

In the United States, the Social Organization of Sexuality found that homosexuality was positively correlated with urbanization of the place of residence at age 14. The correlation was more substantial among men than women. The authors hypothesize that "Large cities may provide a congenial environment for the development and expression of same-gender interest."^[22][23]

In Denmark, people born in the capital area were significantly less likely to marry heterosexually, but more likely to marry homosexually, than their rural-born peers.^[9]

Cultural influences

Further information: LGBT history

Anthropologists had observed that relatively uncompetitive primitive cultures such as those that do not distinguish or reward the best hunters in distinction to the other men in the tribe have virtually no homosexuality.^[24] Miron Baron commented "Some cultures – for example, the Assyrian and Graeco-Roman – were more tolerant of homosexuality. The behavior was practiced openly and was highly prevalent. Sexual patterns are to some extent a product of society's expectations, but it would be difficult to envisage a change in the prevalence of the genetic trait merely in response to changing cultural norms."^[25] This hypothesis had previously been enunciated by Richard Burton as the Sotadic zone.

In the US, there has been an increase number of women developing an attraction for other women. Susan Bordo has stated that when a taboo is lifted or diminished, it's going to leave people freer to pursue things. Binnie Klein has stated that "It's clear that a change in sexual orientation is imaginable to more people than ever before, and there's more opportunity – and acceptance – to cross over the line."^[26]

See also

• Biology and sexual orientation
• Demographics of sexual orientation
• Homosexuality and psychology
• Nature versus nurture
• Xenoestrogen

References

1. ^ "Sexual Orientation and Adolescents". American Academy of Pediatrics Clinical Report. http://aappolicy.aappublications.org/cgi/reprint/pediatrics;113/6/1827.pdf. Retrieved 2007-02-23. "Sexual orientation probably is not determined by any one factor but by a combination of genetic, hormonal, and environmental influences" 
2. ^ ^{a b} Långström, Niklas; Qazi Rahman, Eva Carlström, Paul Lichtenstein. (7 June 2008). "Genetic and Environmental Effects on Same-sex Sexual Behaviour: A Population Study of Twins in Sweden". Archives of Sexual Behavior (Archives of Sexual Behavior) 39 (1): 75–80. doi:10.1007/s10508-008-9386-1. PMID 18536986. 
3. ^ Pediatrics: Sexual Orientation and Adolescents, American Academy of Pediatrics Clinical Report. Retrieved 2009-12-08.
4. ^ ^{a b} What causes a person to have a particular sexual orientation? Page 4
5. ^ Bailey, J.M.; Zucker, K.J (1995). Childhood sex-typed behavior and sexual orientation: A conceptual analysis and quantitative review. 31. Developmental Psychology. pp. 43–55. http://content.apa.org/journals/dev/31/1/43. 
6. ^ Rieger G, Linsenmeier JA, Gygax L, Bailey JM (Jan 2008). "Sexual orientation and childhood gender nonconformity: evidence from home videos". Dev Psychol 44 (1): 46–58. doi:10.1037/0012-1649.44.1.46. PMID 18194004. 
7. ^ Bearman, Peter; Brückner, Hannah (2002) (PDF). Opposite-sex twins and adolescent same-sex attraction. 107. American Journal of Sociology. pp. 1179–1205. http://www.soc.duke.edu/~jmoody77/205a/ecp/bearman_bruckner_ajs.pdf. 
8. ^ Bell, Weinberg, & Parks, 1981; Bieber et al., 1962; Braatan & Darling, 1965; Brown, 1963; Evans, 1969; Jonas, 1944; Millic & Crowne, 1986; Nicolosi, 1991; Phelan, 1993; Biggio, 1973; Seutter & Rovers, 2004; Siegelman, 1974; Snortum, 1969; Socarides, 1978; West, 1959).
9. ^ ^{a b c} Frisch M, Hviid A (Oct 2006). "Childhood family correlates of heterosexual and homosexual marriages: a national cohort study of two million Danes". Arch Sex Behav 35 (5): 533–47. doi:10.1007/s10508-006-9062-2. PMID 17039403. 
10. ^ Isay, Richard A. (1990). Being homosexual: Gay men and their development. HarperCollins. ISBN 0380710226.
11. ^ Isay, Richard A. (1996). Becoming gay: The journey to self-acceptance. New York, Pantheon. ISBN 0679421599.
12. ^ Ruse, Michael Homosexuality: a philosophical inquiry (1988) ISBN 0-631-17553-9
13. ^ Lung, F.W.; Shu, B.C. (2007). "Father-son attachment and sexual partner orientation in Taiwan". Comprehensive Psychiatry 48 (1): 20–6. doi:10.1016/j.comppsych.2006.08.001. PMID 17145277. 
14. ^ Ridge SR, Feeney JA (Dec 1998). "Relationship history and relationship attitudes in gay males and lesbians: attachment style and gender differences". Aust N Z J Psychiatry 32 (6): 848–59. doi:10.3109/00048679809073875. PMID 10084350. http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=0004-8674&date=1998&volume=32&issue=6&spage=848. 
15. ^ Kendler KS, Thornton LM, Gilman SE, Kessler RC (Nov 2000). "Sexual orientation in a U.S. national sample of twin and nontwin sibling pairs". Am J Psychiatry 157 (11): 1843–6. doi:10.1176/appi.ajp.157.11.1843. PMID 11058483. http://ajp.psychiatryonline.org/cgi/pmidlookup?view=long&pmid=11058483. 
16. ^ Bogaert AF (Feb 2005). "Sibling sex ratio and sexual orientation in men and women: new tests in two national probability samples". Arch Sex Behav 34 (1): 111–6. doi:10.1007/s10508-005-1005-9. PMID 15772774. 
17. ^ Blanchard R, Zucker KJ, Siegelman M, Dickey R, Klassen P (Oct 1998). "The relation of birth order to sexual orientation in men and women". J Biosoc Sci 30 (4): 511–9. doi:10.1017/S0021932098005112. PMID 9818557. 
18. ^ Ellis L, Blanchard R (Mar 2001). "Birth order, sibling sex ratio, and maternal miscarriages in homosexual and heterosexual men and women". Personality and Individual Differences 30 (4): 543–52. doi:10.1016/S0191-8869(00)00051-9. 
19. ^ Blanchard R (Sep 2001). "Fraternal birth order and the maternal immune hypothesis of male homosexuality". Horm Behav 40 (2): 105–14. doi:10.1006/hbeh.2001.1681. PMID 11534970. 
20. ^ Puts DA, Jordan CL, Breedlove SM (Jul 2006). "O brother, where art thou? The fraternal birth-order effect on male sexual orientation". Proc Natl Acad Sci USA. 103 (28): 10531–2. doi:10.1073/pnas.0604102103. PMC 1502267. PMID 16815969. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1502267. 
21. ^ McConaghy N, Hadzi-Pavlovic D, Stevens C, Manicavasagar V, Buhrich N, Vollmer-Conna U (2006). "Fraternal birth order and ratio of heterosexual/homosexual feelings in women and men". J Homosex 51 (4): 161–74. doi:10.1300/J082v51n04_09. PMID 17135133. 
22. ^ Laumann, Edward O.; John H. Gagnon, Robert T. Michael, Stuart Michaels (1994). The Social Organization of Sexuality: Sexual Practices in the United States. pp. 308. ISBN 0226469573, 9780226469577. http://books.google.com/?id=3RbyuQAYsdMC&pg=PA561&lpg=PA561&dq=%22large+cities%22+homosexual+rural+likely. 
23. ^ Laumann, Edward; Michael, Robert; Kolata, Gina (September 1, 1995). Sex in America: A Definitive Survey. Grand Central Publishing. ISBN 978-0446671835. http://www.amazon.com/Sex-America-Edward-Laumann/dp/0446671835. 
24. ^ Hendin, Herbert (1978). "Homosexuality: The Psychosocial Dimension". Journal of American Academy of Psychoanalysis 6: 479–96. http://www.pep-web.org/document.php?id=jaa.006.0479a. 
25. ^ Baron M (Aug 1993). "Genetic linkage and male homosexual orientation". BMJ 307 (6900): 337–8. doi:10.1136/bmj.307.6900.337. PMC 1678219. PMID 8374408. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1678219. 
26. ^ Why women are leaving men for other women