P is the grandmother of R, and Q is the father of R. How is Q related to P?

Explanation

1. 01

   P could be R's father's mother. Then Q, R's father, is P's son.

2. 02

   P could equally be R's mother's mother. Then Q is married to P's daughter, so he is P's son-in-law.

3. 03

   Both families fit the two facts and give different answers, so the relation cannot be determined.