It has long been recognized that overweight and obesity tends to run in families, although estimates of the differential contributions of genetic and of various environmental influences to adult fatness have varied widely, depending upon the population used and the methodology applied. The observed familial trends in weight status have both genetic and non-genetic components, and the genetic component is itself quite complex and not fully resolved. A direct or interactive role of environment cannot be questioned: obesity is a disease which is ultimately dependent upon voluntary behaviours (eating, physical activity), and is only widely prevalent in mechanized societies where energy-dense foods are readily and continuously available. However, this fact does not diminish the potential importance of inborn predispositions toward behavioural or metabolic characteristics which would make certain individuals much more likely to become overweight or obese under permissive environmental conditions.
KeywordsObesity Carbohydrate Phenylketonuria
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