Where do ideas come from?

Well you see, when a person loves to write very much, she has an idea. She loves this idea and nurtures it until it's fully matured and ready to take on the world on its own.

And that was my bad attempt at mimicking "the talk." Well, the one you give to a five-year-old.

No, I really do get asked this question often. When I say I'm a writer, people usually get pretty impressed (I don't know why, but they do) and then say, "Where do you get the idea for a story?"

I can only speak for myself, but most of the time when I get an idea, it's from "What if?"
What if a girl found out she had been raised by robots?
What if a kid went on a trip to Mars?
What if someone traveled back in time to the Old West?

Once a "what if" situation pops in my head, I think, "Well, this would probably happen as a result." And then the web just keeps spinning itself until I have a story. Sometimes the idea totally kilters off of my original thought. Once, when I was stirring awake one Saturday morning, I asked, "What if an angel fell in love with a human?"
Now, I quickly realized how sacrilegious that is (at least, for me it was, I couldn't make it coincide with my personal beliefs), but still, that idea intrigued me. So I now, I'm molding my story around the original idea I'd had, but with changes (there are no angels).

So most of the time, I just wonder what would happen in a situation and the snowball effects of it.