Why do you think you are biologically gay

Some studies say it's because of the exposure to a certain amount of hormones in the womb, others say it's because of social (family / father...) and environmental factors etc... In any case, I know no one chooses to be gay and it's predetermined before puberty hits. Question is why do you think you are gay? Do you personally think it's genetic? Birth order? Brain development? Parental influence? What's your opinion on the matter?