The WestermarckEffect is commonly brought up in the midst of [[strike:[[ShipToShipCombat shipping arguments]]]] [[{{Shipping}} shipping discussions]] where [[BrotherSisterIncest incest]], [[KissingCousins cousins]], and [[VictoriousChildhoodFriend childhood]] [[UnluckyChildhoodFriend friends]] are involved. A form of reverse sexual imprinting, the Westermarck Effect serves to suppress inbreeding in humans, working in opposition to the theorized [[http://en.wikipedia.org/wiki/Genetic_sexual_attraction genetic sexual attraction]] phenomenon. The following factors are known to be involved:

* '''Proximity:''' The observed effect applies to children raised in close contact.
* '''Age:''' The critical period for reverse sexual imprinting ends by age 6 or 7.
* '''Age Difference:''' If more than eight years apart, the effect is [[PrecociousCrush greatly diminished for the younger participant]].
* '''Genetics:''' [[NotBloodSiblings Lack of blood relation]] makes no difference.
* '''Gender:''' Women and girls may be more sensitive to the effect [[AllMenArePerverts than men and boys]].
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