Genetics of Obesity: Family Studies

This chapter deals with the genetics of body fat content, regional fat distribution, and nutrient partitioning phenotypes. The comparison of monozygotic (MZ) twins reared apart with MZ twins reared together represents an interesting design to assess the role of heredity with some control over some of the confounding influences of shared environment. During the last 60 years or so, a large number of authors have reported that obese parents have a higher risk of having obese children than lean parents. Nutrient partitioning can be defined in terms of the pattern of deposition of the ingested energy in the form of fat (lipid) or lean (protein) tissue. Cells and tissues of the body are exposed to the same profile of blood substrates and humoral factors. Upper body obesity is more prevalent in males than in females, and it increases in frequency with age in males and after menopause in females.