The Grant family knew the painting was theirs because it still had damage from where their father had struck it with a pool cue.
The 1919 painting depicts a boy sleeping on the ground with his dozing dog beside a hoe he should be using for chores.
The FBI says it ended up with an antiques dealer who thought it was a copy but could never sell it. The agency says he isn’t suspected of a crime.
The Grants say their father paid $50 for the painting after damaging it at a friend’s house.
The painting is believed to be worth more than $1 million.