Alex Wolff plays a child prodigy who goes to college at age 13 in the new comedy “HairBrained.”  He and his brother Nat formed the Naked Brothers band when he was 10, and they starred in a movie and television series based loosely on their lives as kid musicians.  Now 16, he talked to me about working with his brother and his mother and what he learned from his “HairBrained” co-star Brendan Fraser.  But of course we had to begin by talking about the enormous puff of hair that gives the movie its title.

Come on, how much of that hair was yours?

I’m sorry to rain on the parade.  I did let my hair grow for an entire year.  My classmates kept asking why I had a village on my head.  I had giant, giant hair.  It was pretty crazy.  But they did add extensions.  So it was a lot of real and a lot of extensions.  The most hilarious part about shooting the movie was I kept forgetting that I had it.  I didn’t feel it after a while.  I would go into the bathroom and wash my hands and look up at the mirror and start dying laughing because I forgot I had it.  If I had noticed it, I would have been attracted.  I think the movie works because it doesn’t draw too much attention to the hair.  About halfway through, you just accept it and forget about it.

You’re a musician and an actor.  What is the difference between preparing for a musical performance and an acting performance?

In a music performance, it’s my brother and me, we’re ourselves.  No matter where we are, what songs we’re doing, what the set looks like, we have the same rituals backstage.  We put our thumbs together and say “One heart.”  We have all these little ritual we do before the gig, and that’s going to happen forever.  But in acting, it’s a different character every time, so every preparation is different.  Because it’s a specific character, I have to prepare in a specific way.

Your mother, Polly Draper, appeared as an actor on “Thirtysomething” and created your Naked Brothers movie and television series.  Have you learned a lot from her?

The cool part of watching my mom as director, writer, and producer gave me all the training I needed for producing, writing, directing, and acting the short films I have done.  She comes on the sets of the movies I do and gives me notes and I honestly don’t know what I would do without her.  And I have learned a bunch from my brother, Nat.  I watch him all the time because I think he is one of the best actors around.  If you’ve seen “Stuck in Love” or “Admission,” you know what I’m talking about.  I’m not biased!  I honestly think that when I see him in movies, he’s a movie star.  I always look to see what he’s doing.  And people like Ben Kingsley, Kodi Smit-McPhee, Katie Chang , and Parker Posey and Brendan Fraser — that’s the cool part of being an actor.  You get to experience all these other actors around you, see what their processes are and help me cultivate my own.

In this film, you play a kid who acts much older than his age and your character bonds with a character who acts much younger than his age, played by Brendan Fraser.  What did you learn from him?

Yes, the tables are kind of turned for those characters.  That’s what’s fun about the movie.  He’s so funny and energetic and nice to everyone, even everyone on the crew.  That’s something you don’t see with many movie stars.  He was extremely nice to every single person.  That’s something I admire so much and it really reaffirmed my doing that as well.  He showed us that to be a real artist you have to treat every single person like they’re the star of the movie.  That was awesome.

Your character keeps a lot inside.  Is that a challenge for an actor?

I related to the anger that he carried around.  There’s a certain sarcasm and he always has some remark that can outsmart anyone and he uses it as a defense.  But I am very external, so sometimes it would get to be too much when there was a lot going on around me to stay in character and I would have to just go in a room and be by myself for a second.  I couldn’t be as 100 percent social as I would normally have been on the set because I was in that character.  I had to be quiet and angry but also make myself vulnerable.  I was trying to do a lot of different stuff — I hope it comes across.

Your character is a trivia champion — how are you at trivia? 

At movie trivia I’d be pretty good, but I would not have known any of those questions.  They were one of the most hilarious parts of the movie.