I read the recently published booklet Talking to Your Children About Intimacy: A Guide for Orthodox Jewish Parents, by Sara Diament, M.A. It states unequivocally that parents should never lie to children about the topic of intimacy and where babies come from. On the other hand, there is no need to tell them everything at a young age. The key is to give age-appropriate answers and information, and for parents to tailor their answers based on the intellect and personality of their children.
Chapter six (p.p. 50-53) describes a conversation on this topic between a mother and her 10-year-old daughter, and a father and his 11-year-old son. My opinion: The conversation is absurdly graphic for virtually all children of that age, even taking into account the author's disclaimer (p. 10) that parents know their children best and should tailor their message accordingly. I wonder if the author is so naive as to think that such graphic descriptions will not have any serious side effects, at least on boys, whose Nisyonos are exponentially greater.
Indeed, a serious critique of the booklet is that it completely sidesteps a very key issue - the challenges faced by young men before marriage. Because the author ignores that issue, she has no problem endorsing giving an 11-year-old boy a graphic description of marital relations, without considering the consequences.
Overall, I think the booklet gives some useful guidance and is a worthwhile read. However, certain parts of it need to be taken with several grains of salt.