Can someone explain claiming a dependent on state that I didn't claim on federal

I have 2 sons, one who stills lives at home with us. Both of them work, and have already filed their own taxes.
When filing my state return, one early question asks; "Do you have a dependent you didn't claim on your federal return?" If you do, you may be able to claim your dependent on your California return. I have 2, that I didn't claim on my federal return?
Can I claim them on my state? Can someone explain this?
Any help would be greatly appreciated.