Editing Human sexual activity (section)

==Orientations and society==
{{main|Sexual orientation}}

===Heterosexuality===
{{Main|Heterosexuality}}
[[File:Slapende vrouw-Rijksmuseum RP-P-1997-21.jpeg|thumb|A Japanese ''[[shunga]]'' depicting a male and a female in sexual activity]]
Heterosexuality is the romantic or sexual attraction to the opposite sex. Heterosexual practices are institutionally privileged in most countries.<ref name="TRRCGS">{{Cite book|url=https://books.google.com/books?id=_e0yDAAAQBAJ&pg=PA64|title=The Routledge Research Companion to Geographies of Sex and Sexualities |isbn=978-1317043331|first1=Gavin|last1=Brown|first2=Kath|last2=Browne|date=2016|page=64|publisher=Routledge }}</ref> In some countries, mostly those where religion has a strong influence on [[social policy]], marriage laws serve the purpose of encouraging people to have sex only within marriage. [[Sodomy laws]] have been used to discourage same-sex sexual practices, but they may also affect opposite-sex sexual practices. Laws also ban adults from committing [[sexual abuse]], committing sexual acts with anyone under an [[age of consent]], performing sexual activities in public, and engaging in sexual activities for money (prostitution). Though these laws cover both same-sex and opposite-sex sexual activities, they may differ in regard to punishment, and may be more frequently (or exclusively) enforced on those who engage in same-sex sexual activities.<ref>[http://criminal.findlaw.com/crimes/more-criminal-topics/sex-offenders/sex-offenses-overview.html Sex Offenders and Sex Offenses: Overview. From FindLaw.] {{Webarchive|url=https://web.archive.org/web/20110119155906/http://criminal.findlaw.com/crimes/more-criminal-topics/sex-offenders/sex-offenses-overview.html |date=19 January 2011 }} Retrieved 13 October 2009.</ref>

Different-sex sexual practices may be [[monogamy|monogamous]], serially monogamous, or [[Polyamory|polyamorous]], and, depending on the definition of sexual practice, [[abstinence|abstinent]] or [[Autosexuality|autoerotic]] (including [[masturbation]]). Additionally, different religious and political movements have tried to influence or control changes in sexual practices including courting and marriage, though in most countries changes occur at a slow rate.

===Homosexuality===
{{Main|Homosexuality}}
{{See also|Sexual practices between men|Sexual practices between women}}
[[File:Édouard-Henri Avril anal sex detail.jpg|thumb|200x200px|A 19th century illustration by [[Édouard-Henri Avril]] depicting two men engaged in sexual activity]]
Homosexuality is the romantic or sexual attraction to the same sex. People with a homosexual orientation can express their sexuality in a variety of ways, and may or may not express it in their behaviors.<ref name=APAHelp>{{cite web|url=http://www.apahelpcenter.org/articles/article.php?id=31 |title=Psychology Help Center |publisher=Apahelpcenter.org |access-date=30 June 2013 |url-status=dead |archive-url=https://web.archive.org/web/20070928051520/http://www.apahelpcenter.org/articles/article.php?id=31 |archive-date=28 September 2007 |df=dmy-all }}</ref> Research indicates that many gay men and lesbians want, and succeed in having, committed and durable relationships. For example, survey data indicate that between 40% and 60% of gay men and between 45% and 80% of lesbians are currently involved in a romantic relationship.<ref name=WhatIsNature>[http://www.apa.org/topics/lgbt/orientation.aspx#accordion1_content_11 What is the nature of same-sex relationships?] {{Webarchive|url=https://web.archive.org/web/20190120024548/https://www.apa.org/topics/lgbt/orientation.aspx#accordion1_content_11 |date=20 January 2019 }} American Psychological Association, Retrieved 25 December 2014</ref>

It is possible for a person whose sexual identity is mainly heterosexual to engage in sexual acts with people of the same sex. Gay and lesbian people who pretend to be heterosexual are often referred to as being [[closeted]] (hiding their sexuality in "the closet"). "Closet case" is a derogatory term used to refer to people who hide their sexuality. Making that orientation public can be called "[[coming out of the closet]]" in the case of voluntary disclosure or "[[outing]]" in the case of disclosure by others against the subject's wishes (or without their knowledge). Among some communities (called "men on the DL" or "[[Down-low (sexual slang)|down-low]]"), same-sex sexual behavior is sometimes viewed as solely for physical pleasure. [[Men who have sex with men]], as well as [[women who have sex with women]], or men on the "down-low" may engage in sex acts with members of the same sex while continuing sexual and romantic relationships with the opposite sex.

[[File:1925 Wegener Les Delassements dEros 09 anagoria.JPG|thumb|200px|left|A 1925 [[Gerda Wegener]] painting, ''Les delassements d'Eros'', depicting two women engaged in sexual activity]]
People who engage exclusively in same-sex sexual practices may not identify themselves as gay or lesbian. In sex-segregated environments, individuals may seek relationships with others of their own gender (known as [[situational homosexuality]]). In other cases, some people may experiment or explore their sexuality with same (or different) sex sexual activity before defining their [[sexual identity]]. Despite stereotypes and common misconceptions, there are no forms of sexual acts exclusive to same-sex sexual behavior that cannot also be found in opposite-sex sexual behavior, except those involving the meeting of the genitalia between same-sex partners&nbsp;– [[tribadism]] (generally [[vulva]]-to-vulva rubbing) and [[frot]] (generally [[Human penis|penis]]-to-penis rubbing).

===Bisexuality and pansexuality===
{{Main|Bisexuality|Pansexuality}}
People who have a romantic or sexual attraction to both sexes are referred to as bisexual.<ref name="apahelp">{{Cite news |url=http://www.apa.org/helpcenter/sexual-orientation.aspx |title=Sexual Orientation, Homosexuality, and Bisexuality |website=APAHelpCenter.org |access-date=18 September 2012 }}</ref><ref name="glaad">{{cite web|title=GLAAD Media Reference Guide|access-date=18 September 2012 |publisher=[[Gay & Lesbian Alliance Against Defamation]]|url=http://www.glaad.org/document.doc?id=99|archive-date=1 January 2011|archive-url=https://web.archive.org/web/20110101043203/http://www.glaad.org/document.doc?id=99}}</ref> People who have a distinct but not exclusive preference for one sex/gender over the other may also identify themselves as bisexual.<ref name="Rosario">{{cite journal |author1=Rosario M. |author2=Schrimshaw E. |author3=Hunter J. |author4=Braun L. | year = 2006 | title = Sexual identity development among lesbian, gay, and bisexual youths: Consistency and change over time | journal = Journal of Sex Research | volume = 43 | issue = 1| pages = 46–58 | doi=10.1080/00224490609552298|pmid=16817067 |pmc=3215279 }}</ref> Like gay and lesbian individuals, bisexual people who pretend to be heterosexual are often referred to as being [[closeted]].

Pansexuality (also referred to as omnisexuality)<ref>[http://dictionary.reference.com/browse/omnisexual The American Heritage Dictionary of the English Language] {{Webarchive|url=https://web.archive.org/web/20160308133145/http://dictionary.reference.com/browse/omnisexual |date=8 March 2016 }} – Fourth Edition. Retrieved 9 February 2007, from Dictionary.com website</ref> may or may not be subsumed under bisexuality, with some sources stating that bisexuality encompasses sexual or romantic attraction to all [[gender identity|gender identities]].<ref name="bisexuality">{{cite web|access-date=14 March 2011|title=What is Bisexuality?|work=The Bisexual Index|url=http://www.bisexualindex.org.uk/index.php/Bisexuality#binary}}</ref><ref name="Soble">{{cite book|chapter-url=https://books.google.com/books?id=IMTEiTtqqPcC|title=Sex from Plato to Paglia: a philosophical encyclopedia|volume=1|page=115|last=Soble|first=Alan|isbn=978-0-313-32686-8|publisher=Greenwood Publishing Group|year=2006|chapter=Bisexuality|access-date=28 February 2011}}</ref> Pansexuality is characterized by the potential for [[aesthetic]] attraction, [[romantic love]], or sexual desire towards people without regard for their gender identity or [[Sex|biological sex]].<ref>{{cite web|url=http://www.soc.ucsb.edu/sexinfo/article/pansexuality|title=Pansexuality|work=UCSB SexInfo Online |publisher=University of California, Santa Barbara |date=15 December 2009 |access-date=25 December 2014 |archive-url=https://web.archive.org/web/20100721201427/http://www.soc.ucsb.edu/sexinfo/article/pansexuality |archive-date=21 July 2010 |url-status=dead}}</ref> Some pansexuals suggest that they are [[gender-blind]]; that gender and sex are insignificant or irrelevant in determining whether they will be sexually attracted to others.<ref>Diamond, L., & Butterworth, M. (2008). Questioning gender and sexual identity: Dynamic links over time. ''Sex Roles''. Published online 29 March 2008.</ref> As defined in the ''[[Oxford English Dictionary]],'' pansexuality "encompasses all kinds of sexuality; not limited or inhibited in sexual choice with regards to gender or practice".<ref>{{cite web|url=http://oxforddictionaries.com/view/entry/m_en_gb0602230#m_en_gb0602230 |title=Definition of pansexual – Oxford Dictionaries (British & World English) |publisher=Oxford Dictionaries |date=9 August 2012 |access-date=15 August 2012 |url-status=dead |archive-url=https://web.archive.org/web/20110510005353/http://oxforddictionaries.com/view/entry/m_en_gb0602230 |archive-date=10 May 2011 |df=dmy-all }}</ref>

===Avoidance of inbreeding===
Although the main adaptive function of human sexual activity is reproduction, human sexual activity also includes the adaptive constraint of avoiding close [[inbreeding]], since inbreeding can have deleterious effects on progeny.  Charles Darwin, who was married to his first cousin Emma Wedgwood, considered that the ill health that plagued his family was a consequence of inbreeding.<ref>Berra, T.M., Alvarez, G., Ceballos, F.C. (2010) Was the Darwin/Wedgwood Dynasty Adversely Affected by Consanguinity? Bioscience 60:376-383. ISSN 0006-3568.`electronic ISSN 1525-3244</ref> In general, inbreeding between individuals who are closely genetically related leads to the expression of deleterious recessive [[mutation]]s.  The avoidance of inbreeding as a constraint on human sexual activity is apparent in the near universal cultural [[sexual inhibition|inhibitions]] in human societies of sexual activity between closely related individuals.<ref>Degler, C.N. (1991). In Search of Human Nature. Chapter 10, New York: Oxford University Press</ref> Human [[outcrossing]] sexual activity provides the adaptive benefit of the masking of expression of deleterious recessive mutations.<ref>Bernstein H, Byerly HC, Hopf FA, Michod RE. Genetic damage, mutation, and the evolution of sex. Science. 1985 Sep 20;229(4719):1277-81. doi: 10.1126/science.3898363. PMID 3898363</ref>