Fortunately most of us don't have the problem of having to decide what to do with a billion dollars but those that do have to make a choice between giving away large amounts or leaving it to their children. Intuitively it makes sense that those who make their own money are more generous than those that inherited it. I'd always assumed that it reflected the priorities and values of the family --why the family inherited money in the first place instead of donating it. Now there is a study, The Charity of the Extremely Wealthy, that states:
We find evidence that self-made billionaires are three to four times more likely to sign the Giving Pledge and to enter the Philanthropy Top 50 list of biggest pledges, compared with those who inherited their wealth. At the same time, we find that the gap in probabilities between self-made and inherited wealth is much smaller, at about 28%, when looking at the presence in the Million Dollar List. We also find that self-made billionaires give more on average than inherited billionaires do, when measuring total gifts using the Million Dollar List or the Philanthropy Top 50.