My niece is a dna match 2112 cM over 80 segments. She only matches on my maternal side of the family. Her daughter is a dna match of 1118 cM over 46 segments. She matches both my maternal and paternal side extensively. Her father has no matches to my side of the family at all. The ancestry is saying my brother is a half brother. Is it even possible for my grand niece to have dna that her mother doesn't have??