Results of Twin and Adoption Studies updated

Over the years, a number of twin studies have been conducted. One twin study, known as the Minnesota twin study, examined a set of identical twins that were raised in separate environments. Although the twins did not meet until they were almost 40, they shared many similar characteristics. The only explanation for the similarities was that the twins' genes had strongly guided their development.

In fact, the Minnesota twin study led the researcher to conclude: "[On] multiple measures of personality and temperament, occupational and leisure-time interests and social attitudes, [identical] twins reared apart are about as similar as [identical] twins reared together."


Interestingly, adoption studies have also shown the strong influence of genes (or nature). For instance, the Texas Adoption Project found "little similarity between adopted children and their siblings and greater similarity between adopted children and their biological parents."