A computer-implemented method of comparing one or more genetic traits of two users. Each user has a wearable device storing data indicative of the one or more genetic traits, the data having been obtained by an analysis of a biological sample provided by the user. The method comprises: transmitting the data indicative of the one or more genetic traits from a first of the wearable devices to a first computer device using a short-range wireless data connection; transmitting the data from the first computer device to a second computer device over a data network; transmitting the data from the second computer device to a second of the wearable devices over a short-range wireless data connection; and comparing the data from the first wearable device with the data stored on the second wearable device to determine whether there is a match between the users' one or more genetic traits.