Comment by ftxbro

In case you really didn't see my point, it's that it's easier to tell that the mom's side of the family is really the mom's side of the family, than that the dad's side of the family is really the dad's side of the family, biologically speaking. This gives an obvious cultural-evolutionary reason that many would be 'closer' to the mom's side of the family. It's not about whether men cheat more than women or whether women cheat more than men, and it's not making any kind of normative or moral judgement on anyone.