A sibling is a relative that shares at least one parent with the other person. A male sibling is a brother, and a female sibling is a sister. Somebody with no siblings is an only child.

A parent is either the progenitor of a child or, in humans, it can refer to a caregiver or legal guardian. The gametes of a parent result in a child, a male through the sperm, and a female through the ovum. Parents are first-degree relatives and have 50% genetic meet. A female can also become a parent through surrogacy. Some parents may be adoptive parents, who nurture and raise an offspring, but are not biologically related to the child. Orphans without adoptive parents can be raised by their grandparents or other family members.