On Saturday, June 11, 2016 at 1:34:20 PM UTC-7, Nancy Piccirilli via wrote: > I wonder what would be likely to happen in a study of a small island (I > have Aquidneck Island, RI in mind.) Since everyone is cousin to everyone > else (sometimes in several lines), would this make DNA testing of such a > population more difficult? It would make autosomal testing for more than just immediate parentage worthless - if everyone is related to everyone, one way or another, then little can be gained by learning someone is your cousin somehow. Y- and mt-DNA testing would still be of value for an adoptee or illegitimate, as these would still be lineage-specific, even if there are fewer distinct lineages it would narrow things down. taf