This project has the simple objective to reassess the current ALSPAC ID system (which summarises individual identification and relatedness through pregnancy identifiers and birth order) using genetic data. Data and sample identification is an ongoing challenge within the ALSPAC study and studies more generally and the availability of genetic data on (in principle) all participants allows for a re-indexing of samples uniquely and relative to each other in terms of relatedness. There is an academic component to this in understanding the level of relatedness (cryptic or otherwise) in this sample and also a practical aim to this in that this will allow (i) the confirmation of existing IDs and (ii) the proper identification of sample relatedness where sample IDs exist, but no information as to the contribution to family status is available. This will be done solely with genetic data and as such will not be subject to administrative error.