Genetics of 25-hydroxy D3

A new paper in the EJCN examines genetic and non-genetic factors influencing vitamin D serum levels. The authors find 24% of the variability explained by season & intake (& HDL & waist circumference as indicators of body fat) and 29% by genetics. This is somewhat a mystery as 24%+29% is only 53% – where are the remaining 47%?
It seems that the authors are also missing earlier work in this area. We observed a higher heritability (and consecutively higher lod scores) which may indicate that asthma families have some peculiarities in the vitamin D system, yea, yea.