My 23 year old, the youngest of four, told me recently that I never had 'the sex talk' with her. I found this hard to believe and said so. Apparently we never had a formal 'sit down and let me tell you how babies are made' conversation.
My parents did with me. It was a formal evening for Mothers and Daughters. There was a lot of stuff about birds and mammals and diagrams of human reproductive systems. I found it all a bit confusing at the time. It seemed artificial and I could not relate it to my own pre adolescent development.
With my own children, I didn't want the information to sound formal and solely biological, so I adopted the policy of answering their questions as they arose. My youngest daughter found out most of the information through listening to what I said to her older siblings I guess. Not good enough really. In hindsight I probably should have initiated a private conversation with her at some stage.
I think I thought the children would absorb it 'by osmosis' if it (sex and reproduction) was talked about as a natural part of life!
It's not enough to wait for your kids to ask the questions. Some kids will never ask and you, as the parent, should at least raise the subject with them if it has not come up by the age of seven or so. There must be some good books out there that explain sexuality to children. If so, use them, because I think it's harder for you to raise the subject than to respond to their questions.
It's also not enough to tell them the facts without incorporating your values into the conversation. They need to hear what Christians believe about how our sexuality is a highly valued part of how God made us. Talk about the joys of sexuality. Your child deserves to know that his/her sexuality is a wonderful gift, and that expressing sexual feelings in a responsible manner can be a vital and rewarding part of an adult relationship.
The whole idea of sexual relations can be scary for children if not repugnant when they realize their parents have actually 'done it', so emphasising the rightful place of sexual relations within a marriage relationship can be reassuring. With young children, you might also introduce some teaching on protective behaviours for your children, explaining where it is appropriate for other people to touch them and where it's not. Make it clear that they can talk to you about anything relating to this topic and they will not be in trouble.
It really is normal to feel uncomfortable talking about sex with your children. If you did not enjoy openness around this topic with your parents, or you found the discussion formal and awkward, you may find it hard to talk to your children. Lots of parents do, you are not Robinson Crusoe in this.
If any readers know of good books on this subject, either for parents, or to be read to children, please let us know.