age and gender, they obtained an intra-class correlation of .31. This suggests that 31% of variance in job satisfaction has a genetic basis, the estimate would be slightly larger if corrected for measurement error. They also found that evidence of genetic heritability for job characteristics, such as complexity level, motor skill requirements, and physical demands. Personality Some research suggests an association between personality and job satisfaction. Specifically, this research describes the role of negative affectivity and positive affectivity. Negative affectivity is related strongly to the personality trait of neuroticism. Individuals high in negative affectivity are more prone to experience less job satisfaction. Positive affectivity is related strongly to the personality trait of extraversion. Those high in positive affectivity are more prone to be satisfied in most dimensions of their life, including their job. Differences in affectivity likely impact how individuals will perceive objective job circumstances like pay and working conditions, thus affecting their satisfaction in that job. There are two personality factors related to job satisfaction, alienation and locus of control. Employees who have an internal locus of control and feel less alienated are more likely to experience job satisfaction, job involvement and organizational commitment. A meta-analysis of 187 studies of job satisfaction concluded that high satisfaction was positively associated with internal locus of control. The study also showed characteristics like high Machiavellianism, narcissism, trait anger, type A personality dimensions of achievement striving and impatience/irritability, are also related to job satisfaction. Psychological well-being Psychological well-being (PWB) is defined as "the overall effectiveness of an individual's psychological functioning" as related to primary facets of one's life: work, family, community, etc. There are three defining characteristics of PWB. First, it is a phenomenological event, meaning that people are happy when they subjectively believe themselves to be so. Second, well-being involves some emotional conditions. Particularly, psychologically well people are more prone to experience positive emotions and less prone to experience negative emotions. Third, well-being refers to one's life as a whole. It is a global evaluation. PWB is primarily measured using the eight-item Index of Psychological Well-Being developed by Berkman (IPWB). IPWB asks respondents to reply to a series a questions on how often they felt "pleased about accomplishing something", "bored", "depressed or unhappy", etc. PWB in the workplace plays an important role in determining job satisfaction and has attracted much research attention in recent years. These studies have focused on the effects