Discussions on consanguineous marriage within Egyptology usually focus on brother-sister marriages recorded in census returns from Roman Egypt, or royal sibling marriages amongst the ruling Ptolemies. However, no comprehensive review exists of non-royal consanguineous marriage in ancient Egypt despite the economic and biological implications of such relationships. 'Blood Is Thicker Than Water' Non-Royal Consanguineous Marriage in Ancient Egypt presents, for the first time, that evidence for non-royal consanguineous marriage in ancient Egypt has been collated from select sources from the Middle Kingdom to the Roman Period and a method created to investigate the potential economic and biological outcomes of these unions, particularly beyond the level of sibling and half-sibling unions.

The working definition of consanguineous marriage used throughout this study is that used by clinical geneticists: unions contracted between cousins biologically related as second cousins or closer biological kin. This research argues that for some families, and under certain conditions, consanguineous marriage was a preferred economic strategy in terms of gifts given at marriage and in inheritance and that families who married consanguineously may have received greater levels of intra-familial support without the expectation of reciprocity. Although there may have been adverse biological outcomes arising from recessive gene disorders in the offspring of consanguineous marriages, the research suggests that it is unlikely that these physical anomalies or cognitive disorders were distinguished from other medical disorders in the general health environment of ancient Egypt.