Self-confidence is a mixed blessing. I have always applied for jobs that were apparently above my competence level, and then had to work like mad to make sure I succeeded, when the unsuccessful applicants were waiting for me to fail. (Teaching in the Wirral was very incestuous). I used to look at people who were doing similar jobs and think 'I could do it as well as they do'. I have also been told many times that I must be really lacking in confidence underneath but just putting on a good show. If that makes people like me more, I don't mind, but it isn't true.
Being confident does not mean that you fail to recognise the areas where you are less capable. I can't sing, act, paint, reverse neatly, my cooking is hit and miss, I have no sense of fashion and I clearly have gone very wrong somewhere in bringing up one daughter. Other than the last 'failure', I simply tell myself that the things in which I have no talent are not important to me.
I don't know how much is down to nature and how much to nurture. I was , I am told by my sister, a very happy little girl, always ready to 'put on a show', loving the limelight, and my mother and older siblings certainly told me often that I was the best thing since the last best thing!
I have been appalled by the way some members here have been treated by their own mothers - no wonder they sometimes lack confidence.