Gee, I wonder...lets look at one dear ol grampa...specifically regarding George H. W. Bush's daddy.
"After graduating from Yale, Bush moved his young family to West Texas. His father's business connections proved useful as he ventured into the oil business, starting as a sales clerk with Dresser Industries, a subsidiary of Brown Brothers Harriman (where Prescott Bush had served on the board of directors for 22 years)."
Prescott would be grandfather of George W. Bush.  So his family had/has deep ties with the petroleum industry.  I guess that explains some of their policies.