A very wise man I know -- who has 5 kids and knows a LOT about sociology says:
Tell your kids about sex before they reach 10 years old. Maybe around 8 or 9 because ...
1) You should be responsible instead of the school
2) The average age that a male child sees a naked body in our society these days in 2010 is at around age 10.
I think if a healthy attitude towards sex can be instilled upon kids then it will help them to be healthy adults.
....
that being said ...
I personally don't have any kids, so I don't know for definite!
but it's something to think about
yeah thinking about you need to teach your child about these things before the school does makes you feel a bit awful or being awkward as you dont know whats gonna be their reaction.
I'm a cruel and heartless bitch but I’m damn good at it!