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.

The Happiness Project (Revised Edition) (ed. HarperCollins, 2015) - ISBN: 9780062474247