It is both...
Definitely genetic in many cases but a choice by some.
I knew a kid in NOLA that declared himself Gay after a rather normal sexual orientation up to that point. He as much as admitted that he had never considered being gay untill he became enamored of their lifestyle and outlook.
It is not simple. Are prison inmates gay because they engage in homosexual acts? Of course not, life dictates to us but it also affords us choices.
