What is the definition of a family?

We define Family as a group of individuals who belong to any of the following categories:
Mother, father, sister, brother, wife, husband, partner (regardless of gender), son, daughter (including fostered/adopted son or daughter), grandparent, grandchild, parent-in-law, son-in-law, daughter-in-law, sister-in-law, brother-in-law, step-parent, step-child, step-brother, step-sister, or legal guardian.