Special publics Special public: Twins Path FAMILY Twins Number of studies 7 Additional keywords identical, fraternal, monozygotic Related correlational subjects List of Studies on this Public Reference Title of publication Public Koivumaa-Honkanen et al. (2003): study FI 1976 Self-Reported Happiness in Life and Suicide in Ensuing 20 Years. Adults, Finland, 1976-1995 Loehlin & Nichols (1976): study US 1963 Heredity, Environment and Personality. A Study of 850 Sets of Twins. Adolescent same-sex twins, USA, 1963 Kohler et al. (2005): study DK 2002 Partner + Children = Happiness? The Effects of Partnerships and Fertility on Well-Being. 20-70 aged identical twins, Denmark, 2002 Bartels & Boomsma (2009): study NL 2005 Born to be Happy? The Etiology of Subjective Well-Being. 12+aged, mono- and dizygotic twins and their non-twin sibblings, The Netherlands, 2005-2007 Robinson et al. (2001): study US 1986 Dispositional Cheerfulness. Early Genetic and Environmental Influences. Toddlers, same-sex twins, Colorado, United States, followed from 14 to 24 months of age, 1986-1989 Emde et al. (1992): study US Colorado 1986 Temperament, Emotion, and Cognition at Fourteen Months: The MacArthur Longitudinal Twin Study 14 months aged, same-sex twin pairs, Colorado, United States, 1986-1989 Plomin et al. (1993): study US Colorado 1986 Genetic change and continuity from fourteen to twenty months: The MacArthur Longitudinal Twin Study Same-sex twins, Colorado, United States, followed from 14 to 20 months, 1986-1989