I've read back about what I said about "agreeing with" homosexulality and worry I've been misinterpreted.
In the interests of debate (from a philosophical viewpoint, if you like - or just to play devil's advocate), I said that just because something is "innate", it doesn't mean that people (either as individuals, or as society), have to "agree with" it. Hence the example of paedophilia - for some sad/evil/disturbed people, sexual attraction towards children is part of their psyche. They don't chosse to feel that way, there is no known treatment to "cure" it that I am aware of - yet few people would "agree with" it.
That is not to say that homosexuality (or heterosexuality, for that matter) is equivalent to paedophilia. But it does mean (to me) that the argument that you can't "disagree" with homosexuality because people don't choose to feel that way doesn't really stand up.
Having said all that, I think "agree with" and "disagree with" is a strange way of looking at sexuality. One can morally approve or disapprove with the expression of homosexual desires, but it isn't a matter to be "agreed with" in the way that one can agree (or not) with something like civil patnerships, say. So I totally get the point about saying that "not agreeing with" homosexuality is like "not agreeing with" people being black, or the sea tasting salty. Some things just are.
Daftpunk, if you're still reading, I would just tell you not to worry. Your son isn't going to "turn gay" just because he hears about same-sex relationships. After all, you know about them, and you're not gay, are you? My dd is the same age as your son, and came home from school a few weeks ago asking whether it was possible for two girls or two boys to marry - I think children had been talking about it in the playground. Some children thought they could, some thought they didn't. When I told her that they could, she was actually quite relieved - she's of an age where she sees boys as silly, annoying creatures. Children accept these things very easily - especially if you can talk about things in an open and natural way. I do understand your desire to try to "protect" your son and keep his childish innocence - but on the scale of disturbing things about the world your sone is going to find out eventually, I don't really think same-sex relationships are there at all.