Is it normal to talk with siblings about sex?

As we've gotten older, me and my sister have had no problem talking about sex. It's not like something we constantly chat about, but we have no problem discussing it when it comes up. We talk about things like who we've had sex with, what it was like, the weird or awkward or funny things that happened, and so on. I've talked about these things with friends, so I don't see why I can't talk about it with siblings if they're comfortable. We've talked about how awkward our first times were and things that surprised us. I'll admit she also taught me a few simple things about good foreplay. Hey, what are brothers and sisters for if not to help each other out? I thought there wasn't anything wrong with it. But my brother overheard us one time and is now convinced there's something wrong with us. I didn't see a problem with it as long as we're comfortable, but I'm not going to ask people I know what they think about it because I don't know what reputation I could get for asking that kind of question. Even though some of those people are ironically the same ones I can freely talk with about the "chicks" we've "banged" like it's a contest.