What happened to Elise's brother Uncle Ned?Uncle Ned, played by Tom Hanks, was last seen in a second season episode. Ned becomes an alcoholic and the last time we see him he's on the phone calling A.A. It's possible that Ned drove to the meeting and wrecked his car, killing himself.
Marty McFly is Alex Keaton's twin brother, and they were separated at birthLet's say the Keatons had twin boys, but they were so broke they knew they could only manage one at that time. They put the other up for adoption. Then their subconscious disdain about their finances is deeply driven into Alex's subconscious. Marty was adopted by the McFly family.