Twin Studies Another way to study inheritance patterns is to focus on identical twins, which helps scientists separate genetic contributions from environmental contributions.Identical twins are genetically the same.If a trait is inherited, both identical twins will have the trait Scientists conclude that traits thatappear frequently in identical twins are at least partially controlled by heredity.Also, scientists presume that traits expressed differently in identical twins are strongly influenced by environment.The percentage of twins who both express a given trait is called a concordance rate.