Family Relationship Table Brain Teasers

I am married to a widow who has an adult daughter.

My father fell in love with my stepdaughter and married her - thus becoming my son-in-law, and my stepdaughter became my mother because she was my father's wife. My wife gave birth to a son, who was of course my father's brother-in-law and also my uncle, because he was my stepmother's son.

My father's wife also gave birth to a son. That son is of course my brother and also my grandson, because he is the son of my daughter.

Therefore, my wife is my maternal grandmother because she is my mother’s mother—I am my wife’s husband and her grandson—and because one’s grandmother is the husband is his grandfather - so I am my own grandfather!!