About 30% of your character are given by your genes, the other 70% are given by the way of upbringing, your environment and a lot of other things. So I think things like fetishes belong to "the other 70%" (such as being furry or not) and being homosexual belongs to the first 30%.
Anyways, if you're furry or not is somehow up to the way how you define "furry" or "being furry". I tend to say: Furries are people who share a special interest in anthropomorphic animals.
Some people say you need a real "fursona" (oh ... how I hate this word) to be a furry, other people say you just have to be interested in anthropomorphic animals, etc.
This so called "special interest" can be found in a lot of things, such as writing, drawing or role playing (just to give a few examples).
I think you don't need a "fursona" or something (I don't have one myself), so the only person who can decide whether you are a furry or not is yourself.
My ... way too much text with so little content ...
Well, what I originally wanted to say was:
Welcome to the Furry Forums! Enjoy reading, writing or whatever here. I'm sure you'll meet a lot of nice people here.