Jeb knocked up his Mexican-American wife -- they were forced to marry, and if you're a practicing Catholic, it is a big deal if you're not married to a Catholic and not raising your kids Catholic. He's in very thick with the Florida sugar families now (real live indentured servitude in the continental US!), which -- my parents told me the whole story but I forgot it. It's all related somehow.
W had to do something to make up for all that coke and scandal, and becoming born again is really the only option that "wipes the slate clean" -- as with AA, which he used to drops terms from in speeches (he claimed he'd quit drinking long before he actually quit drinking, but I think he did finally quit -- at the beginning of the term it was apparently not that easy to get wine with dinner at the White House) -- you are no longer responsible for anything before your rebirth.
They're really Episcopalians from Connecticut. Neil Bush is, I'm sure, still nominally Episcopalian.
Apropos of nothing, my husband's writing partner was raised in a similar way -- his dad was president of a small university. On his way up, moving around academia in the Northeast, the family joined whatever church was close to campus or on campus, so he was Episcopal, Quaker, and Methodist. He converted to Catholicism to marry his nominally Catholic wife in church (not an easy process), but their kids are in an Episcopalian school, so they lied and said they were Episcopalian and now go to those services every Sunday.