Who's Princess Margaret?
She's the Queen's sister.
She's got two children: one daughter, Sarah, and one son, David.

Who's Diana?
She's Charles's wife.

Who's Mark?
He's Ann's husband.

Who's Peter?
He's Ann and Mark's son.
He's got three uncles: Charles, Andrew and Edward.
He's got two aunts: Diana and Sarah.
His grandfather is Prince Philip, his grandmother is the Queen.