Actual anatomy should be studied with live models and strong light.
…And making a human form look real depends on how you render the shading and shadow to reveal 3-D shapes in 2-D.
And it probably becomes an issue if you are only drawing children’s anatomy.
You have to have parental consent for a child to pose nude for you. This picture not only shows adult male anatomy and deer anatomy drawn from photos, but a nude girl who was 13 when the photo was taken, but 22 when she gave me permission to use it. And, of course, I returned the original photo when this was done. The girl was the daughter of Canadian nudist friends.
This picture was drawn from a model that was actually a nude statuette rather than an actual human being. The important factor in creating nude art is that it is not sexual or intentionally erotic. It does not focus on genitals or breasts, and can, in fact, obscure those parts of the body completely and still be a nude.