William's father was older than his grandfather. How did that happen?

Question

A mother is 21 years older than her child. In exactly 6 years from now, the mother will be exactly 5 times as old as the child.

Where's the father?

Answer 1

William's Father means = Father of church,
and Father of church is older than grandfather of william's.

Answer 2

William's father married to a woman a lot younger, whose father is younger than William's father.
Example :
William 10 yo - William's mother 30 yo - Father of William's mother (William's grandfather) 50 yo
William's father 55 yo