Genetic heritability of obesity exists with the identification of genes responsible for obesity. (Walley et al., 2006). Modifications in single genes disrupt leptin hormone function causing severe obesity. (Farooqi et al., 2006) Genes that create a predisposition towards obesity interact with the environment. Obesity predisposed disease influences the response to obesity treatment. (Choquet et al., 2011)
Obesity is a disease in which environmental and genetic factors interact. In rare cases of severe obesity, a single gene has a significant effect. Mutations in specific genes have a direct impact on the leptin hormone and cause severe obesity. However, the most common forms of obesity are due to the expression of multiple genes. (Clement et al., 2002)
Excessive weight gain is a result of a combination of factors – environmental, genetic, and behavioral. Epigenetic causes influence the prospect of an individual becoming obese. (Campion et al., 2009)
Environmental exposures during critical developmental periods can affect the profile of epigenetic marks and result in obesity. (Herrera et al., 2011) Environmental exposures during early life can induce alterations in the epigenome, leading to an increased risk of obesity later in life. (Van Dijk et al., 2015)
Epigenetic patterns modify due to multiple lifestyle factors like diet, obesity, physical activity, tobacco smoking, alcohol consumption, environmental pollutants, psychological stress, and working on night shifts. (Alegria-Torres et al., 2011)
This brief scientific overview makes us conclude that most obesity is a consequence of epigenetic patterns rather than genetic causes.