Yomiuri recently had a poll. "What is your mom's most common cooking?" 19% those polled responded "it is "it is Nikujag "(simmered meat and potato), 16% said Miso soup, 15% of people responded "Nimono" (Simmered Dishes), No.4 is Curry rice, No.5 is "Imo no nimono"(Potato soy sauce stew).
They don't reveal all the details of their research such as age, gender etc. But most of those responding were likely adults in their 30's and probably not teenagers. Generally speaking, our image for "mom's most common cooking" are those types of food which are kind of simple, but we never get tired of it, even though we eat it everyday. I feel as if Japanese have some sort of soy sauce DNA, during childhood we loved eating hamburg steak, pasta, and fried chicken, and curry. Those in their 20's might respond, BBQ, Beef Bowl, Sukiyaki, Pasta, such large portions and meat intensive dishes. But when we reach a certain generation maturity, I think most people start to enjoy Nimono, Fish, Tofu or such simple, soy sauce based meals, less oily dishes. I suppose in other countries these kinds of changing tastes would happen as well.
Perhaps it is our common perception that is being revealed here. I mean even though the results of the poll were such, I imagine the mother's of those surveyed had much more variety in their cooking. For example, speaking of my mom's common cooking, her jiao-zi, ground meat rolled in cabbage leaves, and tomato stew were always very delicious, yet I would still choose Nimono as my mom's most common cooking. Because the warmth of the kitchen, an apron, a bit of steam rising from a pot of simmering Nimono, the sound of food being chopped on a cutting board, those are the common warm images associated with mom like in these TV commercials.