That was not necessarily true when the Lions played recently at Venice High School. After the game, while his mother, Janet Jones, fell into conversation with other parents on the field, a steady stream of people drifted over to his father to have photographs taken with him. As Wayne Gretzky walked toward the exit, fans continued to give chase. Between poses, he pleaded, “Janet, let’s go!”

Nick Montana’s father watches games from the top row of bleachers, a foam cup of coffee in one hand and a baseball cap low on his forehead. Shortly after Nick threw an interception at Venice, Joe Montana cupped his hands over his mouth and shouted in his son’s direction. Nick was oblivious, but a teammate nudged him and gestured in his father’s direction.

Looking up, Nick Montana saw his father point his fingers at his eyes and motion as if he were trying to bail water out of a boat. He wanted his son to go through his receiver progressions. Later, Nick Montana shrugged and said, “I had no idea.”

He was a toddler in 1994 when his father played his 15th and final N.F.L. season, with Kansas City. Trevor was 6 in 1999 when his father wrapped up his 20-year N.H.L. career, with the Rangers. Because they cannot remember much of their fathers’ playing days, each has Rose Mary Woods-like gaps in his knowledge of his father’s career.

Image Wayne Gretzky with his son, Trevor, who is the backup quarterback on the Lions. Credit... Danny Moloshok for The New York Times

During an ESPN interview last year, Nick Montana said he did not know the player on the receiving end of the Catch. (It was Dwight Clark.) Trevor Gretzky, who is 6 feet 4 inches and took a turn in goal at his father’s fantasy camp in Canada two years ago, drew a blank when his father said he filled the net like Ken Dryden, the 6-4 Hall of Fame goaltender who won six Stanley Cups with the Montreal Canadiens.