I'd say ethnicity is a critical factor in your food choices...
From Frank Oski MD's book Don't Drink Your Milk,
Prevalence of Lactase Deficiency,  Population Group in Healthy Adults
Bantus 90%, Thais 90%, Japanese, Taiwanese 85%, Greenland Eskimos 80%, Arabs
78%, Ashkenazic Jews 78%, ....Finns 18%, American Whites 8%, Swiss 7%, Danes
2%.

-Lou Huis