I’m outside of Atlanta. All the houses I’ve seen built within the last 10 or so years are wired with 12. Mine was built with 12, but a previous resident started finishing the basement using 14.I’m not sure where you’re located but I’m a contractor in both California and Colorado and it’s not normal to have a whole house wired with 12 gauge wire (modern or not). There are certain areas that require a 20 amp circuit (and therefore have 12 gauge wire) but the majority of the house would normally be 15 amp (14 gauge wire).