[hellogoodbyeeee]

What scares me worse than finding out about a mother's actual infidelity is the test, due to statistical variation, falsely reporting infidelity.

Could that happen? Or are the DNA tests correct 100% of the time?

[yorwba]

Since most humans inherit exactly half of their DNA from each parent, it should be pretty obvious when 50% match the mother and the rest doesn't match either parent. So long as enough locations are checked, the probability of getting such a result by chance mutations could be made extremely low.

[dragonwriter]

> Since most humans inherit exactly half of their DNA from each parent, it should be pretty obvious when 50% match the mother and the rest doesn't match either parent.

Assuming the other parent is human, or even from the same tree of life, that's not going to happen, because the actual parent will share some DNA with the purported parent; you'll never get 50% match the actual mother, 0% match neither the mother nor the putative father.

[yorwba]

Ah, right, I was only thinking about locations which are already different between mother and father.

[dv_dt]

There are odd reported cases of people being chimeras and carrying two different genotypes in their bodies. But again, extremely unlikely - but I suspect we will find out more and more about the exceptions which break the expected rollup of model of locations.

https://en.wikipedia.org/wiki/Chimera_%28genetics%29