The aim of this literature review was to study the genetic predisposition to common obesity. Obesity is a major global health concern and is reaching epidemic proportions in both developed and developing countries significantly increasing morbidity and mortality rates. Many illnesses and diseases are linked to obesity such as ischemic cardiac disease and stroke, which are the two most common causes of death globally. Through twin-studies, the heritability of obesity was recognised, and forms the basis for the study into the genetics of obesity. Early focus was given to the candidate gene approach involving genes in energy homeostasis. This revealed several rare monogenic forms of obesity as well as a better understanding of syndromic obesity. The introduction of genome wide scan association studies helped to identify several loci linked to common obesity. However, there still is a major gap in the literature between the estimated heritability and the genetic contribution to common obesity, otherwise known as the missing heritability . There are a range of methods used to study the complex trait of common obesity. Some suggest that common obesity is due to single nucleotide polymorphisms through the genome. These polymorphisms may represent common variants or rare variants. With the decreasing cost of sequencing techniques, it is now easier to study bigger populations and larger areas of the genome. This allows for a better understanding of both the common and uncommon variants, and their role in complex traits. A different approach focuses on studying epigenetics, epistasis and gene-gene interactions. These are still in the initial phases of development and there is a need for further study into these complicated mechanisms. With declining costs and improved knowledge of epigenetics, epistasis and gene-gene interactions, our understanding of the genetic contribution to common obesity will increase further.