Chicago Twin Study
Conducted by:
-Horathio H. Newman, Frank N. Freeman, and Karl J. Holzinger
The Study:
- -First part compared the differences between identical twin pairs to the differences between fraternal twin pairs when the twins are raised together.
- -Second Part compared the differences of identical twin pairs raised together to the differences of identical twin pairs raised apart.
First Part:
- -50 pairs of each type of twin (fraternal and identical)
- -All fraternal twins were those of the same sex
- -Took multiple recordings and tests of characteristics of the individuals involved and noted the differences between twins (height, weight, I.Q., finger ridges, handedness, etc.)
Results and Significance:
-Smaller differences in the characteristics between identical twins than the characteristics between fraternal twins through almost every category/measurement.
-Determined that since identical twins are more similar genetically than fraternal twins, genetics plays a large role in influencing the characteristics of twins.
-Determined that since identical twins are more similar genetically than fraternal twins, genetics plays a large role in influencing the characteristics of twins.
Second Part:
-19 pairs of identical twins who were separated during infancy
-Took multiple recordings and tests characteristics of the individuals involved and noted the differences between twins (height, weight, I.Q., finger ridges, handedness, etc.)
Results and Significance
-In some of the physical traits such as weight, intelligence, and school achievement the average differences between identical twins that were separated are greater than those raised together
-In physical traits such as height, head measure and most others traits, there are very minute inconsistencies between average differences between both types of identical twins.
-Determined that although identical twins raised apart show some data that indicates the characteristics are more similar than those of identical twins raised together, most data is insignificant, thereby proving that postnatal environment does not have as much of an influence on the characteristics of twins as genes do.
-In physical traits such as height, head measure and most others traits, there are very minute inconsistencies between average differences between both types of identical twins.
-Determined that although identical twins raised apart show some data that indicates the characteristics are more similar than those of identical twins raised together, most data is insignificant, thereby proving that postnatal environment does not have as much of an influence on the characteristics of twins as genes do.