Lots of actors keep their age a secret til they are asked,if she went around and told everybody she is in her 30s she probably would not have been cast in Revolution
I must become someone else. I must become something else.
Batfleck and Gal Gadot will Prevail

She's 32 at the time of this writing, she was 18 when she Graduated in the year 2000 from Oak Park High School. When she first was getting famous the school and her old town would brag about her and they talked about how she Graduated in 2000 and you used to be able to see some of her records easier than you can now (she tried to get them all hidden from people).
Since she is able to trick some people into thinking that she is younger, she likes to lie to people about it. I wouldn't doubt it if was directly her or someone that worked for her that kept trying to edit pages around and drop her age down on them. The thing is that she'd have had to have been a super genius that graduated HS at 11 or 12 for the age she normally tries to pretend she is.
Her age wouldn't be a big deal except for that she herself makes such a huge deal out of it. She is ashamed and scared and doesn't like people knowing the truth about it.

In showbiz, 30 is old, especially if you're a woman. Plus she's really just starting out.

I thought she was 26.

Wow, can't believe it. When I watched the Revolution, I thought she was just a teenage girl.

Wow, I thought she was in her early 20s, too. But it makes no difference, I think age is just a number and all that matters is how you look and feel (excluding minors of course).

She is about 31. Which is pretty shocking. She looks 24.

Shes hot to it makes no difference if shes 30 or 40 to me. As for why shes being secretive about her age,well your really not suppose to tell your age,for example if you 30 but look 20 your not suppose to put your age on your resume,but if your asked about age its ok to say

If Wikipedia is to be believed she is 30-31 as they state she graduated high school in 2000

I'm betting around 32-34 you can the in her eyes and hands