it made me wonder if my son's legal guardians should be his parents as neither they nor their children are gifted.
FWIW, DD8 would go to my BIL and his wife, who are both of normal intelligence and have normally-intelligent older kids, if something were to happen to us. She wouldn't go to my sister and her husband, who are both gifted and have a gifted kid about my kid's age. There's more to "fit" than intelligence, and even DD has agreed that she'd rather live with one set of aunt and uncle than the other.