If people are born deaf what languige do they think in?

Holy crap my cousen punched a wall!! I dont know what she thought that would do.

Icewolf: Bleh. I have anger issues. And my knuckles hurt
Elphaba: I thought that was Inora.
Icewolf: no. He blows up buildings when he is angry.
Inora: I-
icewolf: WAIT! This isn't our blog, so you don't have free control! Elphaba, you can ban him!!! *gaspy, happy moment*
Elphaba: I dont want to I like his sassyness.
Inora: My number one saying is 'Sarcasm is an art'
Icewolf: come ON!!!
Elphaba: * laughs in a ninja way* . So Inora whats the funniest thing Icewolf has ever done?
Icewolf: NO!
Inora: Well....probably practically drooling over Yugi-oh every saturday morning.
Elphaba: I know right ugh How much hairgel does he use? Save a little ozone for the rest of us will you!!!
Icewolf: I'm leaving *opens door leading into her blogworld*
Inora: Well that isn't a loss. Now I can party *party*
Elpaba: Yahhh * partay*