The Westermarck Effect is commonly brought up in the midst of [[strike:[[ShipToShipCombat shipping arguments]]]] [[{{Shipping}} shipping discussions]] where [[BrotherSisterIncest incest]], [[KissingCousins cousins]], and [[ChildhoodFriendRomance childhood friends]] are involved. A form of reverse sexual imprinting, the Westermarck Effect serves to suppress inbreeding in humans, working in opposition to the theorized [[ 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]].

For further reading, see Wiki/TheOtherWiki's article on this [[ here]].