Yeah I always wonder when you hear like "99% DNA match!!". So like you confirmed the DNA is probably from a human?
Re:Fingerprints can be hacked
by AnthonyMouse on Monday November 22, 2021 @09:43PM
(#29314052)
The tests generally choose markers that tend to differ between different people rather than the ones that tend to differ between people and animals.
But even then, people use percentages as if everyone's DNA was independent. Which it isn't. Blood relatives have similar DNA.
The one thing DNA is really good for is excluding people. If you have the rapist's DNA and you accurately test it against the suspect's DNA and it doesn't match, it's not them.
The tests also have varying accuracy rates, but people misunderstand what it means. If the test is 99.99% accurate, that doesn't mean that there is a 99.99% chance that the defendant is the perpetrator. It means that in a region with ten million people, you've whittled your suspect list down to a thousand people. If you pick one of them at random there is only a tenth of a percent chance it was them.
This especially problematic when dealing with "DNA databases" because then with a large database you have a high probability of finding a false positive match and the true perpetrator might not even be in the database.