A related study was done by Johansson’s group and his associates involving 18,230 fraternal and identical twins (592 with type 2 diabetes), born between 1926 and 1958. Twins share the same early environment, but identical twins, share same genetic makeup, whereas fraternal twins have different sets of genes.
The overall study results were: Within a fraternal twin pair, the lighter twin would face an increased risk of diabetes. But within an identical twin pair, the lighter and the heavier twin both have the same risk of developing diabetes later in life while faternal twins showed no risk of type 2 diabetes. Thus supporting the idea of the researchers that genetic factors are important in understanding the link between birth weight and type 2 diabetes, and environmental factors, such as poor fetal nutrition.