musicians are people, and some people are gay. so it follows that some musicians will be gay. just because their music happens to be popular does not mean that a) they should not be gay, b) they should not be allowed to express their love for someone else, and c) that they have some special ethical responsibility that straight musicians don't have, to keeping their relationships hidden from the public eye.
music is one thing, but don't forget that these are people too.
if you think your kids shouldn't marry people of the same sex, just tell them, or if you're paranoid, cut out the newspaper articles about it. but it falls to the parent, not to the musician, to take responsibility for it.