Orton, Sarah-Michelle Heritability of serum vitamin D concentrations: twin studies. [electronic resource] - The American journal of clinical nutrition Mar 2011 - 667-8; author reply 668 p. digital Publication Type: Letter; Comment ISSN: 1938-3207 Standard No.: 10.3945/ajcn.110.009423 doi Subjects--Topical Terms: 25-Hydroxyvitamin D3 1-alpha-Hydroxylase--geneticsAdultHumansPublishingQuantitative Trait, HeritableSeasonsTwin Studies as TopicTwins, Dizygotic--bloodTwins, Monozygotic--bloodVitamin D--analogs & derivatives