DAD22, perhaps it's because I posted in haste, but you've missed my point entirely.
What would you say to a Danish couple who are short for Danes, but tall for humans? According to your theory, should they expect their children to be taller than them (because they regress to the mean for Danes) or shorter than them (because they regress to the mean for humans)?
We have numerous people in this thread proclaiming that very high intelligence is normal for their families, and even that they expected their children would probably be gifted before their children even displayed any gifted traits. Of this group of parents with high expectations for their children, we mostly have posters from the group that turned out to be right, because of the nature of this forum. The ones who turned out to be wrong aren't posting here, but we should at least acknowledge that they might exist, and accept that these high expectations may be unreasonable.
Undoubtedly some exist, and I accept (and already accepted) your point about the selection bias that reading only things written by members of this forum imposes. These high expectations
may be unreasonable, but actually I don't see any reason to think so.
I've already explained why I'm not convinced by your theoretical argument. Here's some anecdata to explain why my intuition is that the expectations you're questioning may in fact be quite reasonable. When I think about couples I know who both work in fields where high intelligence is the norm (and as it happens, I can think of many such couples) I can easily think of many who have children who are obviously highly intelligent; I can't right now think of any where the children appear to be less intelligent than their parents [ETA: on further reflection I can think of one case]. Personally I'm more inclined to attribute the effect to environment than to genes, but whatever the balance there, my experience - as observer, not only as family member - supports the kind of expectation you're questioning. If you have evidence or a sound theoretical argument that the expectation is unreasonable, I'd be quite interested in that, since I know my anecdotes are not data.
