Hmm .. it would be really interesting to check out, how many of today's billionaires inherited most or part of their wealth and how many made it big starting from modest backgrounds.
For millionaires (defined as people with >$1MM of capital goods that can be easily reinvested), Capgemini claims that "only 16% of high net-worth individuals inherited their stash"[1]. I'm not sure what the precise definitions are since it's not defined in the article.
The Millionaire Next Door claims that 80% of millionaires in the USA are the first generation in their family to be rich.[2]
I also did my own research looking at (non-Forbes) biographies of the top 10 richest people in the world according to Forbes in 2009. 3 out of 10 came from millionaire or richer families (Eike Batista, Bernard Arnault, Stefan Persson).
If you trust Forbes, you can simply go through their website[3], it classifies each billionaire's wealth as self-made, inherited, or inherited + grown.
Bill Gates also came from a millionaire-or-richer family, so that'd make 4, if that's the cutoff you're using. (He inherited several million from his grandfather, in a generation-skipping trust fund, although I don't believe he yet had access to that money at the time of founding Microsoft.)
Yeah, my logic was that he didn't have/use those resources while building Microsoft. I was trying to divide billionaires into those who built up their wealth without relying much on other resources, vs. those who took existing wealth and grew it.
The tedious way would be to go through the Forbes 400 list and attempt to categorize. Eyeballing the top 20, six are clear mega-inheritances (3x Waltons, 2x Kochs, 1x Mars).
For the rest, it depends on where you want to draw the line for "modest backgrounds". For example, which side does Bill Gates fall on? He's certainly more self-made than Christy Walton, in that he inherited only millions, not billions. But having a multi-million trust fund from your bank-founding grandfather, and a mother who's on several boards of directors, is still considerably above the median in terms of winning the birth lottery (http://philip.greenspun.com/bg/).
The Millionaire Next Door claims that 80% of millionaires in the USA are the first generation in their family to be rich.[2]
I also did my own research looking at (non-Forbes) biographies of the top 10 richest people in the world according to Forbes in 2009. 3 out of 10 came from millionaire or richer families (Eike Batista, Bernard Arnault, Stefan Persson).
If you trust Forbes, you can simply go through their website[3], it classifies each billionaire's wealth as self-made, inherited, or inherited + grown.
[1]: http://www.economist.com/node/17929057
[2]: http://www.investopedia.com/financial-edge/0810/7-Millionair...
[3]: http://www.forbes.com/lists/2010/10/billionaires-2010_Carlos...