If you look at the original study, the biggest single-factor difference (and its not Mormon men that have the 10 years advantage, but Mormon men that have never smoked, have 12+ years of education, are married, and attend church at least once a week) is "never smoked", and the next strongest is "attend church at least once a week" (though whether that's causal or covariant is at least debatable).

And unique features of Mormon practice presumably aren't involved, since the study found the same improvement for members of other religions with the same identified "optimum" features.