According to current research, in the determination of a person's level of happiness, genetics accounts for about 50 percent; life circumstances, such as age, gender, ethnicity, marital status, income, health, occupation, and religious affiliation, account for about 10 to 20 percent; and the remainder is a product of how a person thinks and acts.
Gretchen Rubin (2015). “The Happiness Project (Revised Edition): Or, Why I Spent a Year Trying to Sing in the Morning, Clean My Closets, Fight Right, Read Aristotle, and Generally Have More Fun”, p.9, HarperCollins
