Interesting question. Nobody except DS has ever been tested, so all the following is based on observation. DH and I, yes. My brother also. My father yes (despite a *very* rough and nonacademic upbringing), my mother probably only above average. On my father's side, his brothers and sisters not (mostly below average) - but don't know enough about the grandparents (they were farmers). On my non-gifted mother's side, my uncle yes, likely my aunt, certainly my grandmother - one of the most brilliant people I've known. On Dh's side, father probably, mother definitely not (average), sister not sure (certainly above average, but also dyslexic).