Can DNA test really determine your ancestry or your ethnicity? Should I be worried it is a scam?
Accuracy depends on the algorithm used, the reference data and whether the ancestry of the person taking the test is sufficiently similar to what is in the reference data set. Generally speaking, results from consumer ancestry tests are lacking in accuracy if you have non-European ancestry as there isn’t enough data available. For example, if you are Thai the test will most likely indicate large Chinese relations even if you don’t have much recent Chinese ancestry. This is because there isn’t a specific Thai reference. Similarly, the accuracy is low between diverse groups of people in China because of the use of a single Beijing reference group. Likewise, same thing can be said of acenstry from South Asia, the Middle East or Sub-Saharan Africa. That’s not to say that there aren’t several reference populations available but in my opinion they still don’t capture Africa’s true diversity.
That is a great question. Generally, the accuracy varies. Mostly it’s due to how extensive the studies of different groups of people have been and how well the services collect and analyse the information. The reality is that there have been constant waves of migration, settlement, intermarriage, immigration throughout history.This means that individual populations which might be considered one ethnicity can actually be genetically diverse, and maybe share similarities with other groups that are very different and further away geographically. I guess what I’m saying is that these tests can be accurate; there is a proper science behind this.