Everybody has at least a gay/lesbian cousin, and I´m pretty sure most of us have known about it before they told it to the world... there is no doubt in my mind that there must be a gene, which under certain sociological circumstances can make a person attracted to his/her own gender.
The impact of reseachers finding the "gay" gene is that probably in the future, someone will make and market a "gay cure"... but if someone can make a cure, wouldn´t it also be likely that they could make a "hetero" person "gay"?

(if you go clubbing, then you better watch your drink, or you might wake up gay)