From what I've read, it seems most experts are convinced that homosexuality is the result of genetics (that we're born lesbian or gay), but there is no conclusive evidence so the topic is highly...
first you're going to want to make sure that this is really what you want to do. Also, make sure this person is in fact gay. You don't want any awkward situations. Then, it's pretty much the same as...
Although sexual orientation (whether a person is gay or straight) is genetically determined, there's no statistical evidence that gay men are more likely than straight men to have gay children.