When I was 19, I made a large oil painting of the nerd I would eventually marry. I poured all my attention and care into this painting. It's the only art I have from back then that still holds up as a work I'm proud of today.

I entered it into a judged show at the local art center. It got an honorable mention. I went to see the show with my beloved model. One of the judges came up to talk to me, and highlighted that all the judges really liked the painting. It would have placed, except, you see, the feet were incorrect. They were too wide and short, and if I just studied a bit more anatomy-

I called over my future wife, and asked her to take off her shoe. Being already very used to humoring me, she did. The judge looked at her very short, very wide little foot. Exactly as I'd lovingly rendered it. I would never edit her appearance in any way.

The judge looked me in the eye, and to his credit, he really looked like he meant it when he said "Oh I'm so sorry."

Anyways the moral of the story is that all of those anatomy books that teach you proportions are either showing you averages, or a very specific idea of an idealized body. Actual bodies are much more varied than that.