Editing Westermarck effect (section)

==Research since Westermarck==
The Westermarck effect has gained some empirical support.<ref name=WolfDurham2005>''Inbreeding, Incest, and the Incest Taboo: The State of Knowledge at the Turn of the Century'', Arthur P. Wolf and William H. Durham (Editors), Stanford University Press, 2004, {{ISBN|978-0804751414}}. Introduction</ref> Proponents point to evidence from the Israeli [[kibbutz]] system, from Chinese [[Tongyangxi|Shim-pua marriage]] customs, and from closely related families.

In the case of the Israeli kibbutzim (collective farms), children were reared somewhat communally in peer groups, based on age, not biological relations. A study of the marriage patterns of these children later in life revealed that out of the nearly 3,000 marriages that occurred across the kibbutz system, only 14 were between children from the same peer group. Of those 14, none had been reared together during the first six years of life. This result suggests that the Westermarck effect operates from birth to at least the age of six.<ref>{{cite book |last =Shepher |first=Joseph |year=1983 |title=Incest: A Biosocial View |isbn=0-12-639460-1 |publisher=[[Academic Press]] |location=[[New York City|New York]] |series=Studies in anthropology |lccn=81006552}}</ref>

In Shim-pua marriages, a girl would be adopted into a family as the future wife of a son, often an infant at that time. These marriages often failed, as would be expected according to the Westermarck hypothesis.<ref>Wilson, Margo; Daly, Martin (1992). "Chapter 7: The Man Who Mistook His Wife for a Chattel". In Barkow, J.H.; Cosmides, L.; Tooby, J. (eds.). The Adapted Mind. Evolutionary psychology and the generation of culture. New York: Oxford University Press. ISBN 978-0-19-510107-2. p. 190</ref>

Studies show that cousin marriage in Lebanon has a lower success rate if the cousins were raised in sibling-like conditions, first-cousin unions being more successful in Pakistan if there was a substantial age difference, as well as reduced marital appeal for cousins who grew up sleeping in the same room in Morocco. Evidence also indicates that siblings separated for extended periods of time since childhood were more likely to report having engaged in sexual activity with one another.<ref>Scheidel, Walter. "Evolutionary psychology and the historian." The American Historical Review 119, no. 5 (2014): 1563-1575.</ref>

[[Eran Shor]] and Dalit Simchai revisited the kibbutzim results and found sexual attraction where it had not been acted on. They concluded that any innate aversion needs to be backed up by social pressures and norms.<ref>{{cite journal |last=Shor |first=Eran |author2=Simchai, Dalit |title=Incest Avoidance, the Incest Taboo, and Social Cohesion: Revisiting Westermarck and the Case of the Israeli Kibbutzim|journal=American Journal of Sociology |year=2009 |volume=114|issue=6|pages=1803–1842|doi=10.1086/597178|pmid=19852254 |s2cid=27854996 }}</ref>