Criminals are made when situations and teachings compel them to. Sometimes it's pretty easy to mould the minds of innocent kids with ideas of crime being completely legal. When they grow and start practicing them, the brainwashed kids are either supported by their parent / guardian organization. Take the example of Islamic terrorists.
Now, criminals are born out of factors like Malnutrition, poverty, certain genetic problems, lack of proper care etc.
Here is a beautiful article explaining further.