Sexuality is not like geometry or pottery because, although one may study geometry, one's own geometry never becomes a part of the conversation. With sexuality and especially getting comfortable with talking about it with your kids, one's own sexuality (and theirs!) can quickly become a subject of conversation. If this happens and you don't feel like talking about something simply set a boundary and happily move along. But what if one of your children brings up A VERY BIG THING?
"Mom and Dad, you need to know I'm gay." Or, "Well, I look at porn on the Internet and I don't see a problem with that." Or, "EVERYBODY does sexting, Mom," [bring up patronizing eye roll for dramatic effect). If a parent is getting this sort of disclosure from a young person then that parent needs to understand that something very right is going on here. As a parent I may not welcome these sorts of remarks in terms of their content but I want to be in on the developing conversation my children are having with everyone else with whom they feel safe to disclose.
The truly awkward part of this is being made very aware of the fact that my child has a sexuality of his or her own. They are in a stage of their life when they are trying ideas on for size: "I want to be vegetarian," "I'm a communist," or "I think I want to become a Muslim." You could use these disclosures to preach at or shame your children and watch your influence circle the drain. Or you could say something to encourage the conversation, "IN-ter-esting. Tell me more about that." Which wouldn't be creepy at all when we're talking about sex, would it?
Yes it could, but it doesn't have to be. These early conversations in the safe nest of home and family are the training for future courtship and finding a compatible mate, which is so much more about having a conversation than it is about having sex. We and our kids learn from these safe conversations. So smile, and say "Interesting, tell me more about what makes you think that." And relax. Listen. This is not an emergency — your child is a sexual being. Always has been. And you are beginning to get to know the adult that they shall become. Isn't that worth a bit of discomfort?