Is selfishness a learned behavior or are many people just born that way?

Question

I'm a selfless person by nature. I've always been that way, not by my choice, may I add.
If it were up to me, I rather be like everyone else, say No, and just look out for number one. But my conscience prevents me from acting that way.
When a family member or friend calls me with a problem, I instinctively think of a plan and spring into action to help them.
Can someone shed some insight on this question?

Answer 1

*I think it has to do a lot with the way you are brought up. You do as you see your parents do. Some of that is also in your genes but two people of the same family can be quite different on this matter. Studies have shown that your birth order has a lot to do with personality with the oldest being more responsible and mature than their siblings.*