So my son is five and we've been trying to explain these concepts to him in an age appropriate way. My wife has a gay uncle, so that he just sees that as having two uncles and thinks it's really cool. We don't know personally know anyone trans, so that's been a little more abstract in explaining, but it doesn't seem to phase him.
He has asked me how we know we are boys, so I said well we just know, and asked if he feels like he's a boy and he said yes.
He has asked me how we know we are boys, so I said well we just know, and asked if he feels like he's a boy and he said yes.