I didn't mean to sound judgmental in my earlier post. If any thing it is easier to introduce these topics at a younger age.
For instance we have spent a hour or so each year in the miracle of life tent at the fair,
http://www.mnstatefair.org/entertainment/ag_exhibits/chs_mob.html. Watching sheep give birth is fascinating and naturally brings up these topics in a neutral way.
Last night DS5 and DS7 were discussing animals who get married and don't. We talked about our just spayed cat and how she would have had kittens without a long term partner. No mention of parts... but a reasonable discussion of different norms in the human and animal world and the benefits of marriage(and celibacy before hand if you want to go there). We have similar discussion about gender differences. Typical marriage patterns, which were somewhat more nuanced since we have numerous married same sex friends, including our former ministers. Discussion about parts and mechanics have been rare and short... though forthright.
School sex ed should either be a boring review of matters already discussed by your family... or a warning that these issues are emerging among your kid's friends and should be addresses forthwith according to your family's values. A head in the sand approach is just asking for trouble.
