PASADENA — In “Life Unexpected,” Britt Robertson plays the product of a night of passion between a couple of teens 16 years ago who tracks down her unsuspecting birth parents. Robertson’s own childhood couldn’t have been more different.

“In my case, my mother and I are very, very close,” says the 19-year-old South Carolina native. “I talk to her every day, maybe twice a day. I’ve lived away from home for a couple of years but because of that we’ve gotten even closer. She is like my best friend. We are super, super close.”

The series on The CW is about a parent-child situation at the other extreme. Robertson plays Lux, whose plans to be emancipated after years of bitter foster care land her in joint custody of her birth parents. Her dad (Kristoffer Polaha) is a bar owner with a Peter Pan complex while Mom’s (Shiri Appleby) a controlling radio talk jock. All they have in common — other than Lux — is uncertainty as to how to raise a teenage daughter.

For the record, Appleby is only 12 years older than Robertson.

The relationship between Robertson and her real mom was forged during the years they spent going to auditions, rehearsals and acting jobs. Robertson has been working half her young life in feature films (“Dan in Real Life”) and TV shows (“Swingtown”).

She also thinks it helped she’s the oldest of seven children.

“For the first part of my life it was just me and my mom so we had that bond from the get-go,” Robertson says. “When my siblings were born I always took on the role of mother, too.”

TV and movie critic Rick Bentley can be reached at rbentley@fresnobee.com or (559) 441-6355. Read his blog at fresnobeehive.com.