eccentwrit:

irrelevantcatalyst:

So with the introduction of Josh as a non-Grimm son of a Grimm, I’ve been working on the theory that “Grimm-ness” is inherited as a dominant sex-linked trait and it has to be X-linked dominant inheritance.

Based on these permutations, I would like to take one…

My only question is, and I could just be missing something here, is Josh (the human son of a male Grimm) completely confirmed to not be a Grimm, or is it possible he just hasn’t presented as a Grimm yet? 

And this opens up a whole new aspect to Grimm genetics- like, it’s been established that girls grow into their Grimm-ness much early than boys, which implies that the gene activates during a certain age window. But what triggers it? Hormones?

And it might not have anything to do with age, since girls could have two copies of the Grimm gene and therefore have a higher chance than boys of encountering whatever causes the activation.

(Though I’m leaning towards the age theory, because Nick began seeing Wesen before there was really anything that could work as a trigger)

So that would make being a Grimm a sort of second puberty, right? The same way that Wesen do it- remember that episode with the little girl (I think she was a badger Wesen?) who presented as a Wesen long before puberty- which established that shifting into Wesen isn’t something that presents at birth nor is it something that happens alongside puberty. Maybe Grimms do it the same way.

In that case, unless I’m mistaken, Josh could still end up a Grimm- just an immature one right now. Because, honestly, he doesn’t look that old and Nick was in his mid/late-twenties before he began seeing Wesen.

(BTW, I love doing genetics problems, so this is wonderful)

(Also, where’s the post on Wesen genetic distribution? I’m of the belief that Grimms are more like Wesen than either group would like to admit, so it might help to look at both; see if anything makes more sense that way.)

I mean, they kind of implied that the impending death of a family member could trigger it in male Grimms in the series pilot, which would mean Josh is absolutely not a Grimm since his father died and he didn’t start seeing Wesen. But that theory was never fully explained or expanded upon, and couldn’t be as simple as a traditional familial line of succession, since we later learn that Kelly was still alive when Marie died.

Now if Nick were Marie’s son instead of Kelly’s, and Marie was the older sibling (not sure that’s ever confirmed), then it might make a little more sense, as a traditional line of succession would usually go through the eldest child and their offspring first. But Kelly was already a Grimm, so that doesn’t quite work, either.

Unfortunately, we have so few Grimm families to go on that it makes it hard to come up with a complete theory that covers all bases and closes all loopholes. And I highly doubt Kelly Jr. will clarify matters at all, since he’s a special case with no known precedent and likely won’t follow any of the “rules” of usual Grimm inheritance (whatever those may be).

I do agree that Grimms are more like Wesen than either would like to admit. But all we know from the show when it comes to Wesen genetics is explained thus by Monroe and Rosalee in “Stories We Tell Our Young”:

Wesen + Human = 50/50 chance of Wesen child (Sean is one example)

Kehrseite-Genträger* + Wesen = Wesen child

Two Different Wesen = 

Vorherrscher** (Monroe and Rosalee’s baby will be an example)

*A human who carries a Wesen gene but shows no Wesen characteristics, i.e. cannot woge.

**A hybrid Wesen with a combination of both parents’ traits, with the dominant genes’ characteristics being more prominent. It is not explicitly stated what makes some Wesen genes more dominant.

That explanation is actually part of how @irreverentcatalyst worked out this theory, if I remember correctly. She reasoned that it couldn’t work exactly like that for humans, because of what we knew of Nick and Josh’s parentage. Therefore, there had to be another factor, such as the Grimm traits being linked to sex chromosomes.

We did get a tweet from the writers at one point that the science in her theory was sound, but they coyly refused to confirm or deny it as absolute fact (as they said those “big-M Mythology” details were held close to the chest by the show creators).

Grimm Inheritance