My mom is 30% Spanish my dad doesn't have any Spanish. I'm 29% Spanish. ( (We all took the DNA test) how can I be just as Spanish as my mom if my dad wasn't at all? shouldn't I only be 15%?


3 Answers 3


Your logic is totally correct, and you should be 15% in that scenario.

However, that is assuming the percentages are totally accurate, which they are not. The percentages are likely plus or minus 20%. So your 29% could mean you're anywhere from about 10% to 50%.

It is unfortunate that the DNA testing companies are implying precision in saying that you are 29% instead of giving the range to indicate the level of uncertainty.

Similarly bad, they show you small percentages such as 3% Irish or 1% Eskimo that are more likely than not to really be zero.

  • 7
    Absolutely. There can be serious deficiencies in the models correlating DNA sequences to ancestral populations. A relative took an FTDNA test last year which said she was 30% Scandinavian - exciting, but an unlikely result for an n-th generation Londoner (and she has no childhood memories of helping Uncle Ragnar clean his battleaxe). A few months later, FTDNA changed their model and the analysis dropped to 2% Scandinavian. I doubt many ancestral populations are yet sufficiently well defined in the DNA models to allow any real confidence in these analyses.
    – AndyW
    Commented Jul 24, 2017 at 12:28
  • I totally agree that percentage is treated incorrectly. What does mean that you are "29% Spanish"? There is no thing like pure "Spanish" DNA. Also we need to count that all people have two sets of chromosomes and it makes thing more difficult. What if only one half "is Spanish" - will it be count as 100% or just 50%? The system counting the distances to reference populations is more reliable, but it uses absolute coordinates, nor relative :-( The n-dimensional model can be converted into relative proportions, but they will be difficult to understand....
    Commented Jul 24, 2017 at 14:46
  • And there is no reason for companies like FTDNA make clear guides how to interpret their results. They make their business in muddying the waters
    Commented Jul 24, 2017 at 14:49

Ancestry doesn't give you a Haplogroup. My daughter in law shows 100% east Asian, thats maybe 3 billion people. 23andme breaks it way down to small amounts of Chinese and Korean, which her matches support what we are seeing. A lot of the Ancestry matches do not appear on GEDmatch as good matches. She has only 11 5th cousin matches on FTDNA, I don't think they have a very large database, well thats not their fault, but if you spend money and end up with nothing its disappointing. My feeling is if you are white and looking for you mother or father Ancestry is OK. If your are not white and looking at trying to figure out who you are or clues about your family then 23andme seems to make more sense. Maybe FTDNA will better in twenty years.


Test at 23andme if your looking for ethnic make up. Test at Ancestry if your looking for random close matches. Then transfer you 23andme results to GEDmatch to see your matches Haplogroups.

  • 3
    I didn't minus you, but yor answer is non-sense. 23andMe is just one lab. No better, no worse than others. It really has it's own advantages. More - it is better to obtain test in FTDNA lab because of (1) it's growing family finder matches database (2) ethnic make up calculator of competitive quality (3) better number of tested SNPs with FF chip than 23andMe (because 23andMe also tests for Y and mtDNA with the same chip, so it tests lesset number of autosomal SNPs). And GEDMatch is free service and it accepts many types of raw files - including 23andMe, FTDNA, Ancestry and others.
    Commented Jul 31, 2017 at 7:40

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