(Is homosexuality hereditary?)

I don't think it's any more hereditary than being straight is. (Don't most gay people come from a long line of straight parents?)

Honestly, I think that sexuality is developed with the influence of many factors. Heredity can be one of those factors (Pheromone sensitivity may be inherited, for example), but it's not always the case.

Are you asking if we think there's a "Gay gene"? (My answer wouldn't change, by the way.)