The first, George W. Bush, is a recovering alcoholic. (That’s the language they use in A.A., though he seems to have recovered pretty well by now.) He quit drinking in 1986; today, he enjoys a nice cold Diet Coke. Donald Trump, meanwhile, never got a taste for the hard stuff. Mr. Trump’s older brother Fred succumbed to alcoholism at the age of 42. “He was so handsome, and I saw what alcohol did to him even physically,” Mr. Trump recalls. “And that had an impact on me, too.” For all his many differences with Bush II, the Donald is also a Diet Coke fiend.