I wonder what they sucked at.
From Wiki: His father and grandfather were football players for Indiana University. His grandfather, Rex, also played for the Baltimore Colts (1948–1950) and Detroit Lions (1950), playing in 12 games during his career. He resides in Bloomington, Indiana during the offseason with his wife Alison Miska, to whom he has been married since July 9, 2005. Grossman also has a sister and nephew who live in Lincolnwood, Illinois, and his parents are friends with Archie Manning.
Looks like they sucked at football as well. It's a genetic disorder.