AncestryDNA uses autosomal DNA to trace your roots. The results from this type of DNA can be accurate for 6-8 generations, or 150-200 years. AncestryDNA states that the ethnicity estimate can show the regions where your ancestors were from as far back as 1000 years ago. For suggested matches, the company states that each generation provides less accuracy, so matches that show up as fourth or more distant cousins will be difficult to pinpoint.