Slate’s Brian Palmer, writing in “The Explainer” column, looks into the question of whether identical twins can fool criminal investigators. He writes, “Absolutely. Newspapers are littered with stories of twins who confused police and prosecutors, either intentionally or unintentionally.”Identical twins have distinct fingerprints, because both genetic and environmental factors contribute to fingerprint formation. There are countless situations in which prints have helped police figure out they have the wrong twin.
A new kind of genetic evidence may come to play a role in these cases. Epigenetics refers to chemical modifications to DNA that may change how genes are expressed. A study released earlier this year showed that the epigenetic profiles of identical twins differ at birth, presumably because of small differences in the twins' uterine environments. While no prosecutor has yet used epigenetic evidence to distinguish a guilty twin from his innocent sibling, the findings should put would-be criminal twins on notice.