But Forbes doesn't include any state or state-affiliated families. Considering the influence that is packaged with a billion dollars, it shouldn't be surprising that in many places wealth and political power are more closely tied than they might be in the US or Europe.

How many billionaires in the Middle East aren't counted? High ranking government officials in many countries also are likely billionaires via corruption.

It's unclear what proportion would be inherited vs new wealth, but it's another dimension worth considering.