Why does Teresa Heinz Kerry control the family fortune?

I read in an obituary today for Warren Buffett’s wife, Susan, that she would have inherited her husband’s holdings even though she and her husband had been long separated, although apparently still on good terms and they never divorced.

She could have inherited holdings worth $43 billion.

The obituary stated that the money would have gone to Susan Buffett and eventually a foundation.

This seems like a parallel to the Heinz situation as much of the money is part of a foundation (or trust, I’m not sure exactly which it is)