I don't think acknowledging and discussing with kids the fact that some people are gay counts as "sex education"... unless you count every princess movie and straight love story kids have ever been exposed to as sex education. I think homosexuality could be discussed at a relatively comparable pace... don't get into the nitty-gritty details, but don't erase it.
PS. If you can, try your hand at giving some of the others a bit of feedback. If you already have, thanks, can you do some more?