It turns out that unrelated doppelgangers may have quite a bit in common beyond just twin faces. New research suggests that lookalikes with incredibly similar faces tend to share many genetic variants—variants that don’t just seem to shape their appearance but general aspects of their life. At the same time, other important influences, such as the microbiome, appear to contribute little to their symmetry.
Study author Manel Esteller, a geneticist and director of the Josep Carreras Leukemia Research Institute (IJC) in Barcelona, Spain, is interested in what makes people the way they are. In 2005, he and his colleagues published research showing that identical twins weren’t as identical as they appear at first glance. While they had the same basic genetic patterns, they differed noticeably in their epigenetics: changes in how our genes express themselves, which are caused by environmental or behavioral factors, such as smoking or age.