Psychologists study twins to understand the influence of genes on a particular personality trait or an illness, for example, anxiety. As identical twins have the same DNA, if both twins possess a particular trait, it can be said that genes have a big influence on the trait. read more
Overall, twin studies assumptions remain controversial, says psychologist James Jaccard, PhD, a psychologist who studies statistical methods at the University at Albany of the State University of New York. In response, though, researchers are working to expand and develop twin study designs and statistical methods. read more