Where does confidence come from?

It seems to me that confidence is a tool that offers a huge return for anyone possessing it. If you've got it, you can leverage it in every way possible. A few examples:

1. The confident person seizes big opportunities (or rather creates them) and sees them through to fruition. This could be a business venture, a political opportunity, or something as simple as writing music and playing it live for others to hear. No one wants to take big risks except confident people.
   
   
2. The confident person responds to criticism by converting it to energy and using that energy to further his goals.
   
   
3. The confident person responds to outright failure with an intense review of why he failed. Then he takes this newly acquired knowledge and leverages it to the hilt in his future plans. His failure becomes his asset.
   

But all of this begs the question: where does confidence come from? Genes? Parents? Past success? Good teachers?

Does confidence engender success, or does success engender confidence?