Hayden Panettiere and Milo Ventimiglia will keep their relationship in the family -- on screen that is.

The "Heroes" sweethearts have called it quits, reports Usmagazine.com.

A source close to the couple tells the magazine that it was the age and lifestyle differences that caused the split last week. At 19, Panettiere "is young. She likes to go out in the Hollywood scene and that's not his style," whereas Ventimiglia at 31 "has been concentrating on work on his production company [Divide Pictures]."

Check out photos of Hayden and Milo together on "Heroes."

Ventimiglia reportedly had a crush on his co-star and made his feelings known as soon as she broke up with "Laguna Beach" alum Stephen Colletti. Because of the age gap, they tried to keep their relationship a secret, but finally made it public in late 2007.

On "Heroes," Panettiere plays Claire Bennet, the niece of Peter Petrelli, played by Ventimiglia.