Laura Dern spent this year on the big screen battling cancer — in “The Fault in Our Stars,” her teenage daughter suffers from a terminal diagnosis, and in “Wild,” she’s the sick mom of hiker-memoirist Cheryl Strayed. Dern spoke to Variety at the Hamptons Film Festival over the weekend about both roles.

Did you think you were too young to play Reese Witherspoon’s mom in “Wild”?
We all did, which was really good news for my ego. We’re six years apart. Don’t check IMDb, because they are wrong about my age, and I think they are probably wrong about hers too. It’s so insane that everybody goes by IMDb.

By how many years are they off?
Only by two, but it means a lot. They have that I’m 47. I’m going to be 46, people. I’m really pissed. We’ve got to change that. But anyway, I’m even closer to Reese’s age than people might think if they read IMDb.

Because of the flashbacks, the small age difference didn’t bother me.
She was such a young mom. So I think she and I being peers is really essential to this story and served it in a cool way. Both characters are ageless because memory is elusive. You never really know anything, other than her mother died when she was 44 and how unfair that was to her daughter.

Did Cheryl tell you stories about her mom?
Very much so. I went to Portland in the beginning and I sat on her kitchen floor. I brought my daughter with me, and our daughters are the same age. [Director] Jean-Marc Vallee and I sat on her floor, Reese spent time with her. We really became a family. Cheryl became incredibly essential in the fabric of the every day work. She was with us 99% of the time. Literally, in the middle of her scene, I could ask her guidance or to tell me a story. She was my experience of her mom in such a palpable way.

Did she influence the character’s look?
Physically, everything I wear is her mother’s or a replica of her mother’s, including jewelry.

She let you wear her mom’s actual jewelry?
A bracelet of hers and things that were important to Cheryl. She was very generous to allow us into all her mother’s pictures.

You filmed “Wild” right after “The Fault in Our Stars.” Did you hesitate because both characters deal with cancer?
It taught me a lot in terms of research and how little support there is for cancer research. But they are such different women, and they are such different stories. And they are both Fox movies. I felt like if the bosses are okay with it, I’m okay with it. I just thought it was funny because this is literally the only time I played not only a mother, but a grown-up in a movie. My characters have always been girls. Even on a show I did, “Enlightened,” she’s turning 40 in it, but she’s a little girl — she has not figured out how to be a woman yet. The last time I was a mom onscreen, I was huffing paint and pregnant with my fifth child in “Citizen Ruth.” It’s so hilarious now, young girls after “Fault in Our Stars” are coming up to me and saying, “Will you be my mom? You’re such an amazing mom.” I’m like, “Gosh, you have not seen my other movies.”

You have a new generation of teen fans.
Oh yeah. They loved “The Fault in Our Stars” and it means so much to them. They worship John Green, just like me, so we have a lot to talk about.

Do you think “Enlightened” could ever come back?
I really felt it was done, although with “The Comeback” coming back years later, you can never say never, I guess. You never know what could happen. I think for now we said goodbye. It was very hard for me to say goodbye to Amy because I love her so much.

Both your parents — Bruce Dern and Diane Ladd — are actors. How did you know you wanted to go in the business?
I liked what I was seeing. It was the summer right before I turned 8 that I really fell in love with acting for the first time. My dad was doing a film with Hitchcock and my mom was doing a film with Scorsese. I spent the whole summer watching those two men. It was kind of a no-brainer. At the end of the summer, I said, “Oh, I’m going to be an actress.” I told them I wanted to start studying, and for two years, that’s all I did. And then when I was 11, I told them I had to work, which is so weird and probably a poor choice. I guess there have to be people who will play children in movies. It definitely has its pitfalls and I would not recommend it for children at all.

How did you find an agent?
I met an agent at a friend of my mom’s house, and said to her, “My parents won’t help me — they don’t want me to be an actress. Can I come audition for you?” I got my babysitter to take me to her office after school and did a monologue for her, and she said she’d send me on an audition the next day. I went on the audition and then the director wanted to screen test me for the second lead, so my mom had to find out. It was the Adrian Lyne movie, “Foxes.” I said, “You have to call my mom and talk to my mom.” I was too young for the part, but he gave me a smaller role.