Ava Sambora Modeling ... Heather Locklear's Apple Fell RIGHT Under the Tree

Heather Locklear and Richie Sambora's little girl is ... NOT a little girl anymore -- Ava Sambora is now a full-fledged model.

18-year-old Ava did a photo shoot on the beach in Malibu -- and clicking through this gallery should answer all your questions about how DNA works. She's kind of a genetic sure thing -- and probably a great guitarist too.