When referring to family members, and groups of family, you have gender specific terms and non-gender specific terms.
Mom, Dad, Parent, Parents
Brother, Sister, Sibling, Siblings
Grandma, Grandpa, Grandparent, Grandparents
Son, Daughter, Child, Children
Is there a term like that nieces, nephews, uncles and aunts? Is there a way to refer to nieces/nephews without referring to the gender or to refer to a mixed gendered group? Same thing with aunt and uncle, is there a way to refer to either or both without using a gendered term?