The Mystery Of Discordant Twins

Scientists have long been puzzled by a phenomenon among identical twins called discordance. Despite having the same DNA, aging twins can become discordant for certain traits. One twin can be taller than the other. One twin can become obese while the other stays lean. Identical twins can also be discordant for depression. Discordant twins suggest that our physical and psychological makeup does not arise from genes alone. A landmark 2005 study explained this mystery: Epigenetics.