Eli5 how do dna tests show family relationships despite how massive a dna chain is? How do they know where to look/identity similarity’s?

27 views

Eli5 how do dna tests show family relationships despite how massive a dna chain is? How do they know where to look/identity similarity’s?

In: 1

When you look at a person’s face and see a whole face, you can also break that face down to a few key features – eyes, nose, mouth, ears etc.

So with DNA they don’t look at the whole chain, but specific bits of the sequence. How do they know? The structure of the human genome is fixed in that we know where the sequence for a specific gene is located. Just like on a face we know where the eyes are. We know where the gene that codes for eye colour is.

So we look at the sequence for 2 people and compare a bunch of sites. Now for each gene there might be 2 or 3 different versions of that gene a person can have – like eye colour there are only a few colours a person can have.

If person A has a certain mix of these versions across those sites were focused on, and person B has a lot of those same version, odds are they’re related. Sometimes it’s hard to tell but it’s usually good odds the gene test can tell you.