Full feruchemists?

[noobedmaster7]

In mistborn era 1 it seems if you have feruchemy then you can use all the abilities but in mistborn era 2 it seems there aren't any full feruchemists anymore. What happened to the feruchemists? Is it a genetics thing? If so why didn't we see partial feruchemists in era 1?

[alder24]

This is because out of 300k survivors of the Catacendre a whooping 20% of them were Terrismen, but there were no Feruchemists among them - Sazed was the last one. They still had the Feruchemical genes in them, so their children could have become a Feruchemist, but Rashek's breeding programs and exterminations weakened them a lot. After Catacendre, there was a lot of intermixing between Terris and non-Terris people and the Allomantic genes caused the Feruchemical genes to break down and weaken even further, leading to the creation of Ferrings. Currently, some conservative Terrismen (like Wax's grandmother) try to revert those changes and isolate themselves from other people to increase the purity of their blood and make another full Feruchemist, but so far they have had no success.  

There were Ferrings during the times of the Final Empire, but they were extremely rare because they had to be a descendant of a Terrisman and a non-Terrisman (mostly a noble as they had the strongest Allomantic genes in the population). This simply didn't happen that often because of how Terrismen were treated, with males being castrated, and nobles being required by law to kill any non-noble women they slept with. Terrismen also didn't have many interactions with Skaa, as they served nobles only, so the possibility of a Terrisman to have a child with someone with an Allomantic potential was very low and Ferrings didn't really appear that often. 

Spoiler

Travyl (paraphrased)

Why do the Twinborn in Alloy of Law have only one Feruchemical power, when all previous Feruchemists, in spite of breeding programs, could use all the metals? 

WetlanderNW (paraphrased)

Or were Ferrings always part of the system and we just didn't meet them in Mistborn?

Brandon Sanderson (paraphrased)

The Ferrings are a new development since Mistborn, as the Feruchemists have been interbreeding with the Allomancers. Basically, the Allomancy genes interfere with the Feruchemy genes, breaking it down and creating the limitations we see in Alloy of Law.

Footnote: Brandon's response was very enthusiastic. He noted how perceptive the question was, and obviously enjoyed the discussion. The reporter has expressed their regret at lack of an audio recording to share his enthusiasm.
Alloy of Law Seattle Signing (Nov. 11, 2011)

 

Spoiler

Questioner

In the prologue in The Alloy of Law, it talks about how the guy actually spikes people to the wall. Is there going to be Hemalurgy involved?

Brandon Sanderson

That's a RAFO. Hey, RAFOs! I will say, in Alloy of Law time, Hemalurgy is not well-known and that's not been spread around, and Feruchemy as an art moved like Allomancy did in that you can have just one of the powers. And we decided... Chemings? What did we decide, Peter? Oh, Ferrings. We decided Ferirngs. We couldn't decide between the two of those. It's in the book somewhere.  But anyway, you can have one Allomantic and one Feruchemical. But not a lot of Mistborn and not a lot of full Feruchemists anymore.

Questioner

Do you explain how the Feruchemists came back, because at the end there were a lot of eunuchs and...

Brandon Sanderson

Yeah, well, that's one of the reasons why Feruchemy has been split because it's very diluted now. The Terris people did survive because they made it. And so, the genetic code is there.

Questioner

And so, every once in a while, hereditarily, the gene will come up.

Brandon Sanderson

Yeah. But that's why there aren't very many full-blooded Feruchemists anymore. A thousand years of the Lord Ruler trying to breed it out of the population followed by a cataclysm that destroyed most of the population of the world did them in, yeah.

West Jordan signing (Aug. 4, 2011)

 

Spoiler

Chaos (paraphrased)

Since the dawn of Scadrial, why was Feruchemy isolated in a single distinct population in the world, namely the Terrismen? Allomancy, while rare within the population of Scadrial, at least was not isolated to one population, it was spread evenly, it seems. What is special about the Terrismen that only they get the power of Feruchemy? Does it have something to do with the previous Ascensions before Rashek, with the guardian keeping the power for a time?

Brandon Sanderson (paraphrased)

It's all in the spiritual DNA, which is passed on like normal DNA. However, they are a separate people. They've kept themselves isolated, similar to the Jews in our world. When I asked he said there have been some Feruchemical-mistings [Ferrings] in the past, but they are very rare.

Ancient 17S Q&A (May 1, 2010)

 

[Aeoryi she/her]

Similar to full mistborns: in arc 1, they existed rare, but still present. In arc 2 it was stated that Allomancy had gotten weaker over time and that there had not been any full mistborn in quite a long while, only mistings, which are implied to be the lesser variant of Allomancy/weaker genetics mistborn essentially. Feruchemy is implied to have inheritance patterns directly mirroring that of Allomancy, so it can be inferred that the lack of Ferrings in arc 1 can be explained by "Feruchemy was stronger back then".

We didn't see much of feruchemy period in mistborn books 1-3 and as such we have no confirmation that ferrings existed (or not, I guess) at that time.