Good question. I thought I had read somewhere that the children will be around the "average" of the parents IQ. Not sure where I saw that. I've also read that children tend to move toward the mean (going lower than parents.)
We've got 3 tested kids (so far) and there is about a 25-28pt different between the highest and lowest of the three (still think our lowest child is higher than IQ test is showing...)
We have one child testing higher than the highest IQ parent and one child testing lower than the lower IQ parent. And then one child right around average of the two parents IQs......