Want to make a billion dollars, but sadly not part of a rich dynasty? If you're a middle-aged man born in September who got a degree from Harvard and took his company public, you might be in luck. If you're a woman, you might as well forget it unless you're starting a business in China.

Those are some of the conclusions arrived at  by the folks over at Forbes Magazine, having pored over Forbes' data on self-made billionaires to find commonalities among the world's richest entrepreneurs.

Some shared traits have nothing to do with ability and everything to do with luck or genetics. More self-made billionaires were born in September than any other month, for instance. This isn't far off from the rest of the country; Oct. 5 is the most popular birth date in the U.S., according to Anybirthday.com (nine months exactly after New Year's Eve). Of the 678 self-made billionaires worldwide, 64 have September birth dates.

Read More