12 CFR § 161.24 - Immediate family.
The term immediate family of any natural person means the following (whether by the full or half blood or by adoption):
(a) Such person's spouse, father, mother, children, brothers, sisters, and grandchildren;
(b) The father, mother, brothers, and sisters of such person's spouse; and
(c) The spouse of a child, brother, or sister of such person.