What Relation Would My Brother Be To My Grandchild?

What Relation Would My Brother Be To My Grandchild? If your grandchild is female, then your granddaughter is a great-niece to your brother, and your brother is her great uncle. What do you call the grandchild of your sibling? A grandnephew or grandniece is the grandson or granddaughter of one’s sibling. Also called great-nephew /