How does grandparents' genetics affect a baby's traits?
Each parent passes down half of their genetic information to a child, but that half is itself a mix of what that parent inherited from their own parents. That's why a trait can "skip" a generation: a blue-eyed grandparent's genes may not show up in their own child (who also inherits dominant genes from the other side) and then reappear in a grandchild if it pairs up again with the right recessive gene. For height, the effect is more gradual: the grandparents' genetic background influences the average height their children are likely to pass on — which is why families with tall grandparents tend to "regress" a bit back toward that average even when one parent is shorter. None of these patterns are a fixed rule — they're statistical tendencies, not individual certainties.