Why is the origin of some of my ancestors not reflected in my ancestry results? 

It’s possible that some ancestry present in your ancestors is not reflected in your results. This is especially observed when said ancestor goes back several generations. The populations of these ancestors become diluted over time, with only the most predominant and recent ones remaining in your family tree.

Additionally, the genetic composition of different populations may vary over time due to historical events, migratory flows, and internal dynamics. Therefore, the genetic context of your ancestors’ population may not exactly match the current genetic context of the same population. An ancestor from an ethnic region may have different genetic markers than the reference individuals for that population.