Who says Ghandi didn't? I'm sure they didn't exactly have the best diagnostic psychiatrist in Late 1800s India.
Something went wrong in the cloning?
He's said himself that the pressure of being a famous peacemaker reincarnate (Or cloned, or whatever...) has kinda screwed with him. The original might have had a light case, combined with cloning mutations, and the pressure might have magnified it.
Diathesis-Stress Model. Look it up.
Clones aren't exact copies of their "originals." It's as if a child is born, but the cloned person is both his/her parents. He/she may look and act a lot like the original, but they are a different person entirely.
And then we get into the whole Nature/Nurture debate, not to mention that the causes of ADD/ADHD aren't well known...
I prefer to think that the personalities of the clones are carry-overs of their original counter-parts majorly tweaked by knowing who they once were. Take this for example: Gandhi has A.D.D. because the original Gandhi was a patient, pacifist peace-maker. Naturally, because Gandhi can't live up to his original self, his personality gave into aspects of A.D.D. to counter his former life's restraint and passive nature.
How did the government get the DNA from Ghengis Khan, Gandi, Cleopatra, etc?
Time travel, their history is different, or people saved their DNA in the same fashion that people save celebrity locks of hair?
Or it could be the DNA of people who looked like the historical rendition of him. They're passing them off as the real things. Possibly explaining the Just Bugs Me above.
And would explain how they cloned Jesus.
Hell, I wouldn't be surprised if they indeed DID clone Hitler.
Wait, they DID! Check the episode "Tears of a Clone".
Were the clones aware that they were part of a plan to take over the world? Did they care?
I'm pretty sure they were never made aware. The most they ever seemed to be aware of was that they were clones.
On that topic, why use clones of famous historical figures to take over the world? I could see how Genghis Khan or Hitler could be useful, but Elvis? Vincent van Gogh? Gandhi? GESH had the right idea with the genetically engineered school of tiny Aryan soldiers if world domination was the goal. Then again, it could have been Scudsworth's suggestion, considering his ulterior motives.
Scudworth's idea involved turning the high school into a historical figure themed amusement park. It may be that the board of shadowy figures intended to use the famous leaders and strategists minds to shape some kind of perfect scheme together.
Well, sure, but... Gandhi. Not the person I'd clone for world domination.