FWIWiki: According to geneticist Simon Levay in 1996, "Although homosexual behavior is very common in the animal world, it seems to be very uncommon that individual animals have a long-lasting predisposition to engage in such behavior to the exclusion of heterosexual activities. Thus, a homosexual orientation, if one can speak of such thing in animals, seems to be a rarity.[7] One species in which exclusive homosexual orientation occurs, however, is that of domesticated sheep (Ovis aries).[8][9] "About 10% of rams (males) refuse to mate with ewes (females) but do readily mate with other rams."[9]
http://en.wikipedia.org/wiki/Homosexual_behavior_in_animals
