John Tyler was America’s tenth president. He was born in 1790. He has two living grandchildren.
He was 63 when his son Lyon was born (1853).
Lyon was 71 when Lyon Jr. was born (1924) and 75 when Harrison was born (1928).
Both sons are still alive.
So, there are two men living right now whose father was born in the middle of the 19th century and whose grandfather was born in the 18th century.