Here's what I think: It is one thing to want your child to be healthy enough to be able to achieve at his or her highest possible level (which is where breastfeeding, a healthy diet, an environment free from lead, etc., etc., come in), and it is another thing entirely to want to push that child to achieve beyond what that child would naturally be able to do. I think the latter is what people call "hothousing" and it is neither healthy nor beneficial. It might result in a few increased points on a test here and there, and it might result in a hard-working, driven person. But the trade-off is in the child's autonomy and mental health.
And honestly, though there may be value in high intelligence, there is more value in being a happy, well-balanced person. I have no desire for my child to turn into Hillary Clinton. If she is happy with a job in a blue-collar field, that will be fine by me. If she wants to work hard and compete with other hard-working, extremely intelligent people in a mentally challenging field, that's fine too. I think it is more my job to keep her healthy (and keep her childhood relatively stress-free) than to make that decision for her.
ETA: Not to say that all blue-collar work is not mentally challenging, or that all white-collar work is.
I don't think that at all, but I can't think of a better way to phrase it.
