How did you become cynical and/or skeptical?

Any scientist wants evidence before they are willing to draw connections or make predictions. Skepticism is a wonderful and necessary thing in my opinion. But where does it come from? In particular, where does yours come from? How did you learn to be cynical and skeptical?

This question applies only to those who are cynical and/or skeptical, of course. If you are not cynical or skeptical, you might reflect on why not.