The brothers are suing their parents, who are suing the family for $100,000.
The brothers, who live in San Francisco, say the family’s home in Palo Alto, Calif., was worth $500,000 when they bought it in 2000.
They say they didn’t know they were getting a $50,000 home until the house was sold for $500 in 2012.
The brothers’ attorney, John Sperling, said the family is asking for $50 million in damages and other punitive damages.
Sperling said the lawsuit is about a property that was sold to a man for $3 million.
The family is seeking a court order to prevent the man from selling the property.
A spokesman for the family, Jim Breslin, said they plan to sue the man in federal court.
Breslin said the brothers have been living in a separate home in the Bay Area, and the family had purchased another home in Fresno, Calif.