Sociability is a complex, multidimensional construct. As humans we all have a universal need for interpersonal relationships. Many people maintain rich social connections, boasting high-contact relations across numerous family members, co-workers and friends, while others possess only a few close relationships, and in some instances, are largely socially isolated. Ability to form and maintain these bonds is commonly characterized along two dimensions, social integration and social support. Social integration reflects how extensively individuals are embedded in a social context, both by quantity of social contacts and diversity of social roles, whereas social support refers to the various types of assistance (e.g. emotional and tangible) that people may receive from others or perceive to be available from others. Individual differences in social integration and quality of social support have been shown to be substantially heritable. Up to 70% for pro-social behaviors, including factors such as empathy, degree of social integration, availability of confidants, friend/relative social support is heritable. This implies that as individuals we are endowed with certain traits that affect our ability to form and maintain close relationships with others. Studies (of people of European, Asian, and African descent) have demonstrated that variability in social behavior is at least partly determined by genetic variations in the oxytocin receptor gene (OXTR) that is also associated with empathy trait. In addition, pro-social tendencies are modulated by variants in the CLOCK gene. Interestingly, genetic variations in the CLOCK gene are strongly associated with being an evening person as well as an emotional eater.