Yeah, the genetic argument makes sense there.
Although, in my opinion, homosexuality/heterosexuality has all to with your upbringing. I have not seen enough evidence to consider a 'gay' gene yet.
Today, for example, kids are being taught homosexuality is normal, so you are going to see, possibly, less resistance to Gay's in the future. Those who are told it was not normal will of course be opposed.
There is of course the kind of lifestyle you are born into, such as people around, class status, wealth, etc.