I think terming sexual orientation a "feeling" is rounding it down a lot. Your romantic interests shape the way you present yourself to the world and the way you are received in it, and this social awareness presents really young, even though you usually don't know what the cause of it is. Also, there is over a century of research establishing homosexuality as a sexual orientation. We don't know the exact biological cause, but it is pretty clear at this point (to everyone except the gender crowd and extreme religious people) that homosexuality is innate and unchangeable. We have our earliest accounts of adults in consensual homosexual relationships from ancient Greece (especially men - I'm not referencing pederasty here; there's at least one playwright who was viewed as being really odd and made fun of for choosing to live with another adult man). Our earliest account of someone seeking SRS comes from Magnus Hirschfeld in the 1910s. There's just way less data, way less research, way more RISK, and the most current research (Lisa Littman) makes it abundantly clear that social factors are at work in the current trans craze.