Dakota Fanning ''likes to be silly'' in private.

The 21-year-old actress insists she isn't a good girl all of the time, but believes she hasn't gone off the rails like some of her Hollywood peers because she is very serious about her career.

The 'Franny' star said: ''It's not a negative thing to say, but it's also not 100 percent accurate. I might not be running around being insane, but I'm also a 21-year-old who likes to be silly. Just because I don't flaunt those parts of my life doesn't mean I don't do some of that privately.''

But the starlet, who first found fame when she was seven in the film 'I Am Sam,' thinks some people will always consider her a child.

The blonde beauty told the May issue of NYLON magazine: ''I've made my peace with the fact that there will be some people who, for the rest of my life, will believe I'm, like, 9 years old. I have this joke that I'm literally going to be 35, married, and pregnant and people are still going to say, 'Oh my god, you grew up so fast! I can't believe it!' And yeah, sometimes when you're 21 years old and people are still saying that, you just want to rip your hair out. But I'm OK with it. I know who I am.''

Meanwhile, Dakota, who currently studies Women in Film at New York University, isn't a huge fan of social media.

She said: ''I kind of long for when there was more mystery to how movies were made. Now everyone's goal is to know everything about everything.

''I feel like if I did it, I'd start to measure my experiences by how good of an Instagram it's going to turn into. And I don't want to be living my life trying to see it all in a square, trying to get a photo.''