In an interview with
Mihaly Csikszentmihalyi in a hungarian magazine
168 ora says that 50% of the happiness is genetical, 10-15 is the environment and 35-40 is depending how the person organize his/her life.
http://www.pursuit-of-happiness.org/history-of-happiness/mihaly-csikszentmihalyi/csikszentmihalyi-on-happiness/