We knew that a deficiency in Vitamin D could result from too little exposure to the sun. We knew that not getting enough in our diets or in supplements could cause a vitamin D deficiency.
Research now seems to indicate that we may have a genetic predisposition to whether we having enough or whether we will have a deficiency in Vitamin D.
"Researchers in the SUNLIGHT Consortium (Study of Underlying Genetic Determinants of Vitamin D and Highly Related Traits) analyzed data from 15 epidemiologic groups that included nearly 34,000 whites of European ancestry. The team looked at vitamin D concentration levels in the blood as well as genetics. Vitamin D insufficiency was defined as concentrations lower than 75 nmol/L (nanomoles per liter) or 50 nmol/L."
Three gene variants may be associated with vitamin D insufficiency. These three are linked with cholesterol, metabolism of vitamin D and the transporting of vitamin D through the body. The more of these gene variants you have, the more likely it is that you may have a vitamin D deficiency.
http://www.webmd.com/news/20100609/genes-may-play-arole-in-vitamin-d-deficiency?ecd=wnl_day_061010