Okay, so because the Justice department successfully caused the breakup of Standard Oil, Rockefeller's great-grandfather had a hand in the beginnings of almost every major oil company in the US today. Senator trust-funds's money is that much dirtier. Instead of the "global warming" gases caused by Exxon-Mobil's products, he can take credit for those of Chevron and Marathon and Conoco.
And BP. :)