Actually, I had the impression that Asian skin might have more oils to convert to Vitamin D. Before responding I did a little research. Found this quote regarding “ceramides” in skin of various races. Ceramides are a family of waxy lipids (fats). “Sugino et al37 measured ceramide levels in the stratum corneum of four different races and found the highest levels to be in Asian skin. Significantly less ceramide was noted in Caucasian skin (20.4±8.1ug/mg) and the lowest level was found in Black skin (10.7±4.7ug/mg). This was similarly observed by Hellemans et al47 who quantified ceramide levels after hydrolysis and analysis of corresponding sphingoid bases, showing the least amount of lipid in the stratum corneum of Black skin.”
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4086530/
Thus it would appear that Asians have the most which if they are part of Vitamin D conversion would enable living further north. In addition I have read that American Indians used bear’s grease to protect their skin which might also enhance D production/absorption. More research needed. In addition it makes sense that Africans living in high sun environments would have the least lipids in their skin. Very dark African Americans are always trying to use some skin cover to prevent having an ashy gray color from dry skin.
OTOH...that doesn't explain how their descendants, living in Europe ( re Attila the Hun/Hungarians ) "lost" the Ceramids in such a short time, which they apparently did, since outside of slightly slanted eyes ( but retaining the white eyelid folds, which Asians don't have ) they look 100% white.
OTOH...Eskimos have ( perhaps it's "had", since I don't know how prevalent it still is ) a predisposition towards having what's called "strawberry" birthmarks. This is a repressive gene occurrence for Hungarians as well; which pops up rarely, but does pop up.