I went to a talk at our local library about how to talk to your kids about sex. A wonderful author came and gave the talk and she said start young. The younger they are the more accepting they are of the facts and the less embarassed they are about it. They grow up knowing it and not being embarassed by it. She said start by teaching them proper body part names (not cutesy ones) as it also helps deter sexual abuse as sexual predators are put off when kids are more educated about body parts and sex. I picked up her kids book which has pictures of everything and tells everything and I have no problem reading it to my kids. I started reading it to my son at 2 when we had baby#2 on the way and I did not leave out any details. His respose was "oh ok, can I go watch cartoons". I remember knowing nothing at all until I was like 9 or 10 and wow was I embarassed having "the talk". My friend's mom who is a Dr sat my sister, my friend and I all down and gave us the talk together (as mky mom died when I was 7). I would have much preferred knowing at a younger age.