Sex,
Having a soon to be 14 year old daughter this section hit close to home. My wife and I haven't told her lies about sex but we have certainly held back some things. Pregnancy and STD are important topics to understand but even more so are the emotional aspects. Sex can be a powerful binding and richly rewarding part of a relationship but only so far as each partner treats it with the appropriate respect. You may have casual sex but it comes at the cost of less meaning for sex in a committed relationship. I don't want her having sex now not because it may cloud her judgement but because I want her to be able to have something much better in the future.
Swearing,
Minor point. I tell my kids not to swear (and don't hardly swear myself) for the same reason I don't let them track mud in the house. I just think it's ugly. I hope that doesn't set me off as less educated.
Death,
There is too much to talk about in this kind of forum. I just wanted to note that talking about religion is far less controversial than talking about parenting.