OK, sidestepping the backbiting that seems to be getting away from the point -
I do think that parents should be involved in their children's sex education. It doesn't have to be a formal 'birds and bees' discussion. I have told all my girls that if they have any questions about anything at all ever, they can ask me, and they have, in varying ways, because they are very different from each other.
The vital message to put in place is the concpt of pregnancy and STD's from unprotected sex.
The other vital ingredient is honesty - all my children knew, and know, thaty if they ask a question about anything under the sun, they will receive as honest an answer as i can give them. If I don;t know the truth, I will find out, and get back to them - this helps in displacing the playground nonsense that teenagers fret about until someone puts them right.
Communication is a big part of family life - listen to, and talk to your children. It's part of loving them.