While some super-rich people give directly to causes, most dynastic families are keen for their philanthropy to go through private family foundations, probably due to the considerable tax deductions they receive for setting them up and donating to them on an annual basis. In fact, America’s top 50 wealth dynasties have created 248 family foundations between them – five per family on average – and as of 2018 these contained $51 billion in assets.
While the private foundations are used to give funds to charity, the IPS report notes how the money held in some foundations is "not always moving out as fast as it might". In fact, the 248 foundations paid out grants to causes at a median rate of just 5.7% of assets, only just over the 5% legal minimum limit. And as many as 98 foundations distributed grants at a rate below 5%.
It's also worth noting that only four billionaire descendants of dynastic families have signed up to Bill Gates, Melinda French Gates and Warren Buffett's Giving Pledge, which would see them give away half of their wealth in their lifetime.