Problems with 起こす and the suffix 還り


Context: A kid who is part of the Nanaya tribe is inside a dark forest when he
sees a man with a red eye who looks like has gone mad and is standing in a
field.

> 七夜では紅赤朱と口伝される。  
>  くれないせきしゅ。  
>  一言にいえば極めて旧い、先祖 **還り** を **起こした** 混血の事を指す。  
>  小我としてのリセイが大我としてのリセイに飲まれて正気ではなくなってしまった者の事だ。 赤い凶眼は、憑かれたモノの証だという。
>
> The red crimson has been made into Nanaya's popular tradition.  
>  Deep crimson vermilion.  
>  If I had to say it briefly it points to a very old mixed race which caused
> the return to the ancestors.  
>  Someone whose rationality has himself as been swallowed by a bigger
> rationality.  
>  They say that those red unlucky eyes are evidence of being possessed.

一言にいえば極めて旧い、先祖還りを起こした混血の事を指す

I do not understand this 起こした. Is it to awaken or to cause?

先祖還り="Return of the ancestors" or "Return to the ancestors"?

を起こす="To cause something" or "To awake to something" or "To awaken something"?

Edit:  
先祖還り= Atavism  
So I presume

> 一言にいえば極めて旧い、先祖還りを起こした混血の事を指す

could be

> If I had to say it briefly it points to a very old mixed race which awoke
> its atavism.

or

> If I had to say it briefly it points to a very old mixed race which caused
> atavism.

Which would be better?




Here ~を起こす is a verb whose subject it is that goes through a change in state
or an event denoted by its object.

Often used in connection with medical conditions of some kind:

(~の)発作を起こす：to have a fit (of ~)  
貧血を起こす：to have an attack of anemia  
脳内出血を起こす：suffer a cerebral hemorrhage  
ヒステリーを起こす：to have a fit of hysteria; go hysteric

混血 I think refers to an individual/individuals rather than a whole race; but
it is seemingly modified by 極めて旧い(very old/antiquated), which is not a common
descriptor of a person. This creates a conundrum. One explanation is that
極めて旧い in fact hitches only on the 先祖(ancestor) part of the word 先祖還り(return to
ancestor; atavism), with the result of 「旧い先祖・還り」(return to a very old
ancestor), which, though possibly an abomination to some minds, does make
sense (kind of?) And that's what I went with for my translation attempt:

> To put it in a few words, it refers to a mixed-blood that has undergone an
> atavistic reversion to his/her ancient ancestor.




I think 起こす here is "to cause/develop" as in 心臓の発作を起こす or アレルギーを起こす. The noun
還り ("returning") is not something that can sleep. If the phrase were
(体内に眠っている)先祖の血を起こす, then _awake_ might be better.

I read 先祖還り as 先祖 **に** 還ること (returning _to_ the ancestors). I think 先祖還り in
this context is someone being like his 先祖, not his 先祖 actually returning to
life having their own will.

