Family member.
(8) Family member. The term family member is defined with respect to a taxpayer as a child (or descendant of a child); a sibling or step-sibling; a parent (or ancestor of a parent); a step-parent; a niece or nephew; an aunt or uncle; or a son-in-law, daughter-in-law, father-in-law, mother-in-law, brother-in-law or sister-in-law. A spouse of any of these family members is also considered a family member.