Why are twins often used in genetic studies?

Twins are often used in genetic studies primarily because identical twins share nearly the same genetic makeup, allowing researchers to differentiate between the effects of genetics and environment on various traits or conditions. By studying identical twins—who have virtually identical DNA—scientists can more easily assess how environmental factors might influence their development, behaviors, or health outcomes. This ability to control for genetic variations is what makes twin studies particularly valuable in understanding the heritability of certain traits.

In comparison, other choices are less suitable for this kind of research. For instance, while fraternal twins can show some variation in genetic similarity, they are not genetically identical, which complicates the analysis when trying to isolate genetic factors from environmental ones. Twins being easier to observe in nature and having higher mutation rates are not the primary reasons they are used in genetic studies, as the focus is on the interplay between shared genetics and different environmental influences rather than their prevalence or mutation characteristics.