The usual concerns in US politics about Catholics are whether they're automatically against abortion, and for Jews it's whether they're automatically supporting Israel. Neither fear seems to actually come true -- views on both matters align more with the political party of the politician than with their religion: a Catholic Democrat is more likely to support abortion than a non-Catholic Republican, and so forth.
As far what elements in a person's nuture contribute to their personality I don't think it's truly possible to figure that out (there are simply too many variables in play) and also I don't think it's important -- I don't care why Politician X is a raving lunatic, or why Politician Y is an insensitive jerk, or why Politician Z is so stupid, what matters is not putting them into office and mitigating the damage they achieve once they're in. Let their biographers, therapists, and grand juries worry about the background.