Sarchasm

I suffer from a condition lovingly titled by a friend of mine as "Open mouth, insert both feet, close, chew quietly."This is also frequently refereed to as sarcasm. What does this have to do with work or disabilities? Absolutely nothing, but I figured that it was about time you heard about something else for a change. A friend and I went to a concert the other night and got into a conversation about sarcasm and how some people are more sarcastic than others. I happen to be the more sarcastic, she happens to be the nonsarchastic one. Why is it that some people find the need to be sarcastic and others don't. I find it fascinating how differently people grow up and each persons personality is. Is it a matter of nature or nurture, or a mixture of both?