Minnesota Twin Family Study

The Minnesota Twin Family Study is a longitudinal study of twins conducted by researchers at the University of Minnesota - Twin Cities. It seeks to identify the genetic and environmental influences on the development of psychological traits.

Principal investigators are David T. Lykken, Ph.D., Matt McGue, Ph.D., William Iacono, Ph.D., and Kevin Haroian, B.A. It involves several independent but related projects:


 * Minnesota Twin Registry
 * Minnesota Twin Study of Adult Development
 * Minnesota Twin Family Study (Male Project)
 * Minnesota Twin Family Study (Female Project)

Its original goal in 1983 was to establish a registry of all twins born in Minnesota from 1936 to 1955, but it has now added twins born between 1961 and 1964. Twin studies are valuable to researchers because twins share 100% of their genes in identical twins and on average 50% of their genes in fraternal twins. This allows researchers to estimate the heritability of certain traits. Participants are asked about academic ability, personality, and interests; family and social relationships; mental and physical health; physiological measurements. Of interest to researchers are prevalence of psychopathology, substance use, divorce, leadership, and other traits and behaviors related to mental and physical health, relationships, and religiosity.

The Minnesota Study of Twins Reared Apart
In 1990, the project published the results of their study of twins reared apart.

Criticism of Reared Apart Twin Research

 * Farber, S. L. (1981). Identical twins reared apart: A reanalysis. New York: Basic Books.
 * Joseph, J. (2004). The Gene Illusion: Genetic Research in Psychiatry and Psychology Under the Microscope.New York: Algora. (2003 United Kingdom Edition by PCCS Books)
 * Joseph, J. (2001). Separated Twins and the Genetics of Personality Differences: A Critique. American Journal of Psychology, 114, 1-30
 * Kamin, L. J. (1974). The Science and Politics of I.Q. Potomac, MD: Lawrence Erlbaum Associates.
 * Taylor, H. F. (1980). The IQ Game: A Methodological Inquiry into the Heredity-Environment Controversy. New Brunswick, NJ: Rutgers University Press.