I think most of you guys have pretty good points. I have three kids as well 3,4 and 7 and I will also do the cooking. My costs are a bit more than Fat Boys but not by too much. I am pretty "grocery" savvy when it comes to savings which helps a lot.
All that being said, I don't think anyone would disagree with the blanket statment of "in general, healthy food is more expensive than processed crap." FatBoy and I are probably outliers when it comes to healthy eating for large families.
On a side note: While thanksgiving and christmas foods are being marketed things like frozen wildcaught salmon are on fire sale right now!!! Buying a bunch and sticking them into the deep freezer!