Submitted by Beneficial-Elk-8207 t3_11apn21 in explainlikeimfive
from what i know they test up to 24 markers/loci to get conclusive result (assumming there's many markers in our DNA), is it possible to get two different results if two labs did not test the same exact markers/loci? like lab 1 test loci 1-24 and lab 2 test 25 to 54 loci.
You're assumption that different labs may test different loci is probably true, depending on whichever test kit they have sourced to conduct their paternity testing. That being said, testing different loci should still come up with the same results, so different test couldn't wouldn't explain the differing results unfortunately
Yep, the way they get to their answer might be different but it should still give the same answer (you are the father yes/no) if the method is sound.
Do paternity tests give a certain yes or no now? I needed one for citizenship purposes years ago and the report we got only had a percentage, like, “there’s a 99.995% chance of paternity” or some very high but slightly under 100% percentage, but not a solid yes or no. They explained to us at the time that no test could be 100% certain, so a yes or no answer would be invalid.
That's correct, there's no true 100% certainty. But as a matter of statistics, you can interpret some threshold level match as an effective yes/no.
from what i saw on google, 99% considered conclusive.
I see, so regardless of how many test taken /methods/different lab/s as long the sample came from the same person (assuming there's no human or lab error) it should come up with the same results?
Yes (assuming the labs are using valid testing methods)
One possibility is a blunder where two identical samples generate different results. Lab A didn't follow protocol, or a reagent was a bit old, or a power glitch or similar. This is independent of whether they are using the same method, same loci, etc.
This type of error is common enough that there are special checks routinely included. This might be a "standard" sample run in the same batch. They know what result the standard is supposed to have so if it's wrong then your sample may also be wrong.
Of course that doesn't fix a different kind of blunder where your sample got mislabelled or switched, or spoiled while in shipping. Those get checked by blind "traveller" standards. That's where occasionally the lab QA person mails a standard in labelled just like a normal sample. It's not a perfect check because it just detects sloppy handling of the traveller, not sloppy handling of your sample. But it does serve to weed out systematic problems
Another possibility is a random match or mismatch. If a given loci is expected to be present in, say, 50% of the population, and there's no correlation between loci, then the chance that two different sources match at 23 loci (but not the 24th). is around 1/2^24,. Which is one in about 16 million.
I see, so its very unlikely to come up with different results regardless of how many test taken if we eliminate possible human and lab error.
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It shouldn't be. If both tests were performed properly they should both get the same result. What good is a paternity test that fails to accurate determine paternity?
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A_Garbage_Truck t1_j9t9ida wrote
assuming neither test was fudged its not statistically likely, so 2 different tests might mean one of them was fudged and you might require a 3rd.