Panettiere's mother "adores" Ventimiglia

Milo Ventimiglia "fits in perfectly" with the family of his new girlfriend Hayden Panettiere.

The 30-year-old actor confirmed that he is dating his Heroes co-star Hayden, 18, at a cast party before Christmas.

"Hayden's mom adores Milo. She thinks he's so cute," a family friend told People magazine. "She tells her friends that he's her boyfriend. She's very proud."

"He's even met her grandparents," the source continued. "He fits in perfectly with the family. Milo jokes around with her little brother. They're buddies."

The couple - who play Peter Petrelli and Claire Bennet on the hit NBC drama - have not yet spoken publicly about their relationship.