1. A computerized method for transforming digital images representing a plurality of individuals into one or more predictors of characteristics of a pair of individuals, comprising: for each individual of a plurality of pairs of individuals, storing one or more digital images representing the individual in a memory operably connected to a digital computer; using the digital computer: annotating the one or more digital images with a plurality of reference points; associating a data set about the individual with the one or more digital images representing the individual; computing one or more metrics using measurements derived from the plurality of reference points; for each of the plurality of pairs of individuals, associating a pairwise data set about the pair with the one or more digital images representing the individuals comprising the pair; and determining one or more indicators usable for predicting characteristics of another pair of individuals, wherein the one or more indicators comprise one or more principal indicators, and wherein determining the one or more indicators comprises: determining, for each of the one or more metrics, at least one principal relationship using the particular metric computed for the individuals comprising the plurality of pairs and data from the data sets about the individuals comprising the plurality of pairs; selecting at least one of the one or more metrics based on the determined principal relationships; determining one or more principal functions based on the determined principal relationships; and determining one or more principal indicators by combining the selected metrics combined according to one of the determined principal functions.