Why don't ethnicity estimates from Ancestry DNA matches add to 100%?

Question

I have noticed that some of my Ancestry DNA matches have ethnicity matches that do not add to 100%. Is that because for some matches, Ancestry is only showing the ethnicities where we match?

Comments

Also has to do with the fact that it is Probabilities, which are a variable, rather than a constant

Answer 1

The ethnicity estimates are based on selecting a few parts of tens of thousands and guessing at the ancestry based on similarities with others.  It isn't exact science and it changes every year.  My parents and I tested >10 years apart and I have ethnicities that they do not have.  This means that after they told me my ethnicities, they adjusted their test criteria and use it for new tests but never bothered to chance my results.  They get a lot of blowback when they change already published results so now maybe they let sleeping dogs lie.

They do have a disclaimer and one that we should all take seriously: the ethnicity percentages are for fun.  We should consider them like like we do the switch on the toaster - connected to nothing.

Answer 2

Under DNA settings there are two options:

"Your DNA matches can see your full ethnic regions and Genetic Communities™."

and

"Your DNA matches can only see the portion of your ethnic regions and Genetic Communities™ they have in common with you."

So if the ethnicity does not add up to 100% your match has selected the second option.

Comments

Thanks for the quick response! -- Robert