My husband also had a great, great, grandmother who was native American married to a French Canadian trapper. She may have been Cree. He grew up in Iowa, and his mother never told him until a few years before he died. She was ashamed. I probably have a little Mongolian Tartar from my Prussian German ancestry. Our one son is very dark haired, dark eyed and slightly olive skinned. He was at a museum once and said he really thought he looked a lot like the Crees. Our other son has medium brown hair, very dark eyes, high cheekbones, and somewhat almond eyes. He had a slight epicantic fold as a baby. He is also dyslexic like his father. Now, in a recent thread I discover that my husband may also have Neanderthal ancestry, with his bright red hair, freckles, clear blue eyes, hairy body, short legs, long strong torso, big bones, heavy brow ridges, warrior temperment, and Scots ancestry. I wonder what his mother would have thought of that? Isn't genetics fun, can't wait for the new scientific developments.
Regarding dolicocephalic heads, there is an interesting nutrition factor. Head shape can be influenced by nutrition factors, Adelle Davis, "Let's Have Healthy Children". When number 1 son was a baby he had a broad full head. After age 1 his head began to narrow like mine, but not his red head father. Then I read in the book that this is a sign of Vitamin D deficiency. I started giving him cod liver oil and his head gradually became rounder again. Vitamin D is formed by sun in oils on the skin, then absorbed into the body where it affects bone formation. If it was more cloudy in the period around 13kya, or if more clothes were worn the fact that more skulls were dolicocephalic may not have been racial, but environmental. I believe that in ice age times it was drier (less cloudy) people might have been less likely to wash the skin oils off in the cold, ergo, brachycephaly.
Interestingly, the Eskimos have no source of fresh fruit, but they still get plenty of vitamin C. They drink a lot of seal oil. It is extremely high in pretty much everything a growing boy (or girl) needs. Good stuff.
I was in an Anthropology class many years ago, and there was a Japanese kid in class. He was about 6'2" tall. The instructor assumed that the kid was not full-blooded Japanese. Wrong. His parents were born in Japan and moved to the US before he was born. His father was about 5' tall, and his mother was a bit less. That was one embarrassed Anthropology Professor.
Nobody in his family (still in Japan) was as big as he was, not by a long shot. He could not speak Japanese; they did not teach it to him. He was not raised on traditional Japanese food, as his parents wanted him to "be American". They raised him on meat and potatoes for dinner, with lots of cow's milk and cereal for breakfast. He grew up big. Who'd'a thunk it?