Somatotype is the combination of physical characteristics that individuals have depending on their genetics and habits Somatotype Dr. It was divided into three groups by William Sheldon in the 1940s. These are Ectomorph, Mesomorph and Endomorph. When it first emerged, it was thought to be unchangeable and it was said that the physiological and psychological qualities of the individual were affected by the somatotype, but in line with current information, the views that the body somatotype should be considered more physically were effective.