There has been a lot of forensic work done lately by matching DNA samples to relatives. For example, parent or sibling would match approximately 50% DNA with the sample.

In SR, do auras of related people have similarities, enough to argue for similar relationships? So, could one say the following?

"This person's aura is really close to the one I seek. They must be related."

Is there anything in the books that is definitive on this subject?

I suspect we share 94%+ of our DNA pattern with dogs and 60% with bananas, so 50% seems low for blood relatives. Then again, my blood relatives are inadequate at even being bananas, so you may have a point.

Related to your question: if an Awakened identical twin bonds a focus, can the other Awakened identical twin activate it themselves? I suspect not. I suspect that when one goes on an Astral Quest to alter one's fundamental astral passport, effectively you return as a new identity (eg, old Wards will bounce you now) and I expect this makes your aura as distinct from anyone else's as any arbitrary stranger would be.

Even when identical twins are exposed to as similar an environment as we can manage (same access to education, clothing, food, care, etc.) they do not tend to respond and behave identically so the colours and flashes in their auras could be quite different. But we do have clones in SR, and Eclipse Phase does have resleeving egos into morphs... so I wonder if you were to find a way to install one person's Essence into two vat clones, would they have recognisably similar auras? I suspect they would initially, but would differentiate over time.

I don't think I have seen anything in the books suggesting aura inferences are canon.

Perhaps the closest in canon I'm aware of would be to use a genetic relative as a Material Link to Ritually track someone. Which might suggest there could be tethers of "Magical Link" between the auras of people who are especially emotionally important to each other. Going by the 6DoS principle, given enough time one could presumably follow such tethers to any arbitrary target.

In my (imaginary) SR, auras = fingerprints.

I don't remember anything RAW.

That said it one of those things I could easily see them just doing in a novel. So I figure it's something a GM could rule works in their game.

But if a GM doesn't think it should work, I'm unaware of anything a player could counter with.

Thanks, folks. The fingerprint opinion makes some sense to me. The material link idea is cool, but things someone has handled for a while can also be a link, so maybe it is a bit out there.

If the situation comes up, I'll test the GM's view.

I'd like to say you can tell people are relatives just as well as you can with normal perception. Just like when you see a family, you'll notice similar facial feature traits among family members.

So with that said. No.

Wouldn't that be more about the relationship between the individuals than about the DNA? In other words, wouldn't a beloved (and non-incestual) spouse be a better link than a distant sibling?

From our SR4 House Rules:

In first world nations, at least, police use Quicksilver Mana Sensitive Film Cameras (Arsenal, pg. 67) to capture astral signatures and then digitize them, giving them a searchable database of magical signatures. (Pro Tip: Shadowrunners, clean up your astral signatures or the cops will take a photo and use it against you in the future.)

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So, this would definitely be the GM's call. Does a genetic relation translate to a magical signature relation? For me, that would a no. Magical aptitude isn't genetic, so I don't see how signature matching to your relatives would be a valid approach.

Was Unexplained Genetic Expression (UGE), then, just scientific mumbo jumbo for something the eggheads couldn't explain?