"Where the C allele indicated lactase non-persistence and the T allele indicated lactase persistence, the study found that women that were homozygous for the C allele exhibited worse health than women with a C and a T allele and women with two T alleles. Women who were CC reported more hip and wrist fractures, more osteoporosis, and more cataracts than the other groups.[13] They also were on average 4–6 mm shorter than the other women, as well as slightly lighter in weight"

For colder, European climate, bigger weight/size is preferable (and bigger body requires stronger bones). Not so for warmer/Asian areas where smaller body size is ok and thus more favorable, in particular because it requires less animal protein, etc... which is less available there than in Europe.