How is our sense of humor formed?

I don’t think sense of humor has anything to do with genes or whatever. Some people laugh at everything. Some people rarely laugh. There are people who take everything seriously, can’t understand sarcasm or jokes, and those who think every little thing is funny. But why? Where does it come from? Does it have to do with our childhood and how happy we were? I’ve for some reason been wondering about this lately…what do you guys think? Why are certain things funny to one person but not another? Does it have to do with your opinions on things, or culture, or WHAT?

I know personally I find a LOT of things funny. It doesn’t take much to make me laugh. But often times things that are supposed to be funny to me, aren’t. Stand up comics…I rarely ever laugh. But if I see a picture of an anteater, I’m on the floor. I don’t know why though. I’ve always been a happy person, in my childhood as well, so does that contribute to me laughing at everything as well? Anything?