Your opinion is only that - opinion.  There is nothing factual that you can point to that says people "pick" their sexual orientation the same way people pick religions or anything like that.  And in fact there is much more to suggest some people are actually born with inherent attractions to people of the same sex....which is why you see homosexuality in every country, on every continent, in nearly every species, across the globe.

You suggesting that people "pick" their sexual orientation also suggests that you picked your orientation at some point in your life, or that sexual orientation is fluid in that one can change their preference at any given time.  While that may be true to some extent, I have yet to ever meet anyone who is against gay marriage or gay rights, ever be able to tell me when they chose to be straight, or admit that they could have a sexual relationship with someone of the same gender anytime they wanted to - if they wanted to.