Hayden Panettiere cuddles up to lil’ bro Jansen as they attend the Whaleman Foundation Benefit at Hollywood’s Beso Restaurant last week.

Jansen, 15, just recently completed work on The Lost Medallion: The Adventures of Billy Stone with Sammi Hanratty. The flick, which follows a young Billy and his best friend Allie as they’re transported back in time 200 years, is set to hit theaters in 2011.

Big sis Hayden has been an active supporter of The Whaleman Foundation which promotes research and conservation for dolphins and whales and their ocean habitat.

15+ pics inside of Hayden and Jansen Panettiere…