<P> Like many other medical conditions, obesity is the result of an interplay between environmental and genetic factors . Studies have identified variants in several genes that may contribute to weight gain and body fat distribution; although, only in a few cases are genes the primary cause of obesity . </P> <P> Polymorphisms in various genes controlling appetite and metabolism predispose to obesity under certain dietary conditions . The percentage of obesity that can be attributed to genetics varies widely, depending on the population examined, from 6% to 85% . As of 2006, more than 41 sites on the human genome have been linked to the development of obesity when a favorable environment is present . The involvement of genetic factors in the development of obesity is estimated to be 40--70% . Some of these obesogenic or leptogenic genes may influence obese individuals response to weight loss or weight management . </P> <P> Although genetic deficiencies are currently considered rare, variations in these genes may predispose to common obesity . Many candidate genes are highly expressed in the central nervous system . </P>

The percentage of the inheritance of obesity that is accounted for by genetic factors is about