This therapist agrees with you. See the section, "Where Does The Fetish Come From?". Childhood. It starts out as a fascination and becomes sexualized during puberty. Further down, she explains that fetishes are deeply embedded and cannot be changed. So the advice is to accept and work with it, and not be ashamed. It is a part of who you are.
http://www.therapywithcare.com/Article_Fetish.html
Not really. From 2005:
http://www.webmd.com/sex-relationshi...there-gay-gene
"Since sexual orientation is such a complex trait, we're never going to find any one gene that determines whether someone is gay or not," says Mustanski. "It's going to be a combination of various genes acting together as well as possibly interacting with environmental influences."
And an article from 2014 citing several studies:
http://www.telegraph.co.uk/news/scie...rch-finds.html
There are many theories involving different factors and the point is that no one knows for sure.