There is not much in common. It is not talent. It is not ethnicity. Not personality. Not schooling. Not religious affiliation.

The one common characteristic I have found is books. People who become worth a damn are readers.

Even more importantly than being a reader: the most important commonality is when they started to read.

I just read in Wikipedia about Howard Zinn:

Both parents were factory workers with limited education when they met and married, and there were no books or magazines in the series of apartments where they raised their children. Zinn’s parents introduced him to literature by sending ten cents plus a coupon to the New York Post for each of the 20 volumes of Charles Dickens’ collect