Sure. Naruto, as we all know, is a clown. He is serious when he needs to be, but sometimes even then he is a clown. We know how he acts most of the time. It's what makes him a good hearted fun to watch develop character. But because of that, you can deduct that from his maturity a bit.
Obito, on the other hand, is completely serious all the time. He does what he does out of lost love, and other reasons which we don't know just yet. My guess is that he wants to become the God of the entire shinobi world just like Madara. Anyways, it's like a chemical that goes to the brain that transforms the normal eye or sharingan eye to either a Sharingan or Mangekyou Sharingan. That being said, an Uchiha doesn't choose to be the hate filled people they unfortunately become. As the 2nd stated, the Uchiha cherished love above all others. When they lose it, they just go insane. We witnessed it first hand with what I consider the darkest chapter in Naruto; when Obito goes on a rampage after seeing Rin die. They just can not help themselves as it is in their blood in a sense to become what they do.
