Re: Math, chemistry, engineering?
You know, you can have a lot of conversations with kids about relationships without getting into sex. It's not like kids didn't learn about moms and dads and families years before they learned exactly where babies come from. Keep things on the "Becky has two mommies" level if they're young. Kids won't get freaked out by things unless they're taught to.
I do kind of wish there was some cultural space in between putting a minority group in the dog house and putting it on a pedestal, though. Pendulums suck.