Facial marks as biometric signatures to distinguish between identical twins

There exists a high degree of similarity in facial appearance between identical twins that makes it difficult for even the state of the art face matching systems to distinguish between them. Given the consistent increase in the number of twin births in recent decades, there is a need to develop alternate approaches to characterize facial appearance that can address this challenging task that has eluded even humans. In this paper, we investigate the usefulness of facial marks as biometric signatures with focus on the task of distinguishing between identical twins. We define and characterize a set of facial marks that are manually annotated by multiple observers. The geometric distribution of annotated facial marks along with their respective categories is used to characterize twin face images. The analysis is conducted on 295 twin face images acquired at the Twins Days Festival at Twinsburg, Ohio, in 2009. The results of our analysis signify the usefulness of distribution of facial marks as a biometric signature. In addition, contrary to prior research, our results indicate the existence of some degree of correlation between positions of facial marks belonging to identical twins.