Not all labs are created equal. Some are accredited—like they have a gold star from the government. Others? Not so much.
If the lab is sloppy, they could misread the markers. Or they might use a test that only checks a few points of DNA. Fewer markers = higher chance of a false positive. Think of it like a fingerprint with only three whorls.
A reputable test checks 20 to 40 genetic markers. A cheap test might check 10. That’s like guessing your friend’s birthday with only the month. Close, but no cigar.
The “Oops, I’m the Father” Twist
Here’s a sneaky one: false exclusion. The test says “not the father,” but he actually is. How? If the child has a rare genetic mutation. That one weird marker might not match Dad’s, but everything else does. A good lab will flag this and ask for a second sample.
On the flip side, false inclusion is rarer than a unicorn in a desert. But it can happen if the alleged father is a close relative of the real dad. Like a brother or a cousin. The test sees “family” and shrugs.
Can a Paternity Test be Wrong? - Genomes Unzipped
