Rachel Bilson was a ''dumb ass'' during her time on 'The O.C'.

The 31-year-old actress shot to fame as Summer Roberts in the teen drama which launched in 2003 but admitted if she could go back and change how she was during her time on the show, she would.

She told Britain's Cosmopolitan magazine: ''I didn't have any idea how much 'The O.C.' would change my life. I thought I knew everything, but now I look back and think, 'You were a dumb ass! What was your problem?'''

Rachel - who was previously in a relationship with her 'The O.C' co-star Adam Brody - is currently dating Hayden Christensen and revealed she is hoping to settle down and start a family soon.

She said: ''Thirty is a whole different thing; you can slow down and focus on family. Starting a family one day is definitely something I look forward to.

''My parents' divorce didn't make me cynical about love and marriage. I've always been a big romantic, and I look forward to all those things. I've been in a relationship for six years, and I'm happy...To have a partner is one of the greatest things. I've always been a fan of love...I'm an emotional person; I go with my heart before my head every time!''