European vs American Skull Size

from fastcompany.comover dinner i mentioned to my husband that I read an article in fastcompany magazine about a guy (Tom Davies) who builds custom eye glasses. In the sidebar of the article there was a nifty list of reasons to get custom glasses. Item number 1 is that “americans’ ears are typically set about 10 mm farther back than europeans”. This sparked interesting conversation. is this true and if so why.

my take on it…. environment is one factor, i think american’s health habits etc.. might an influence. also genetics. this is where it gets interesting. what is the genetic makeup of the “average” american. i’m guessing it’s still european caucasian. if so, why is there difference in skull size? take my genetics for example, aside for an unverified rumor of gypsy, i’m 100% european mix — english, dutch, german, scotch, italian. a little of everything. i’m curious now, do i have an american head or a european?