Through factor analysis, personality can be narrowed down according to the five factor model, which holds that there are five aspects of heritable personality traits: openness to experience, conscientiousness, extraversion, agreeableness, and neuroticism. Research has shown that personality is 50% heritable, but not always. There are two aspects of personality which are related to happiness. There is a strong relationship between extraversion and happiness, in that the more extraverted a person is (or behaves) the more happy he/she will be. The other aspect of personality which has a strong relationship to happiness is the genetic predisposition to neuroticism. The more neurotic (emotionally unstable) a person is, the more likely he/she is to be unhappy.