Luke Bryan’s boys have impeccable manners, and the singer says he’s got his wife to thank

This December, Luke Bryan and his wife Caroline will celebrate 15 years of marriage. It's a feat they've accomplished by always having fun together, the star tells People in a new cover story interview.

But despite all the goofy family fun, Luke adds that it's also important to the couple to set a positive example for the kids they're raising, including their sons --13-year-old Bo and 10-year-old Tate -- and college-aged nephew, Til