Why does it has to be caused by a disorder? And as said, it is probably a highly complicated equation that determines our sexuality, it seems like genes are a part of that (note I do not believe in a gay gene, it is probably a combination of genetic factors).Either way, it hardly matters. If Bisexuals also suffered from a genetic disorder, then wouldn't that mean they'd exhibit a "normal DNA pattering" and a "abnormal patterning". Since neither this nor a Gay Gene has been found, one can logically conclude that heredity plays little to no influence on the likelihood of becoming homosexual.