So, I have an interesting question that was brought up in my group's session last night. They have to determine a way to discover the identity of Brood Brothers in a Genestealer Cult (other than checking for mutations) and they tossed the idea around of checking their blood. Taking samples and sending it off for tests is one thing, but the question was, would cultist blood be a different color? I mean the Tyranid swarm are xenos so its safe to assume that most, including purestrains wouldn't have red blood, but what about the hybrids and human appearing brethren of the cult? I've seen nothing on the lexicanum or in the genestealer cult codex to support either way so I'm curious to hear others' theories.

Dunno about colour, but the genetic makeup of a hybrid would robably be different to a human's

if there blood is copper based insted of iron based it would be blue

Since they are born normally and are "bloody" close to humans I would guess their blood is of "normal" red colour, though DNA testing would show adnormalities.

Differently-colored blood would generally fall under the heading of "mutation".

Hmm, I'll have to agree with he comment that likely the more human cultists would still have red blood, but an analysis would reveal irregularities. Ultimately it will be up to the players on how they think they'll be able to uncover the cultists but should they go down the route of testing the blood, I'll keep the sample analasys in mind.

So here is an interesting question,

what happens if one of the characters accidentlly gets infected with Genestealer blood? Would it slowly start to mutate the player?

Salcor

I'd say its red, maybe surpirsingly brightly coloured (contains more oxygen)?

copper-based blood isn't as efficent as iron, and tyranids are big on biological efficency. so as cool as blue blood is, I'd say its unlikley.

Salcor: Personally, I'd say no, that would only be possible if their blood contained cells or viruses capable of transfering their DNA into the new host.

Certainly though you'd find weird xenos stuff in there. Dunno how much DNA would be in their blood though, i'm pretty sure human blood cells don't have any.

Agmar_Strick said:

Ooo, I like that. It's the same color but a little brighter. Of course, maybe not noticeably brighter unless you've trained yourself to spot it, but definitly brighter. If they weren't directly interecting with the Magus I might have made it noticable, but well, I want to keep his true identity secret until later.

our blood is red due to the iron in our blood containing oxygen aka rust gives the colour, but it is stated that genestealer infected have a high urge to reproduce this might be due to an extremely high hormon level of a certain hormon, that might be detected by a correctly tuned auspex- scanner, maybe this magos grant them the tuning specifications by a dataslate that can tune there auspex equibment.

Check out the first Ciaphas Cain novel. In it they are facing a similar problem and there is brief mention of auspex settings and tracking the genestealers and their ilk.