"Possible Halo" option needed

I would appreciate seeing “Possible Halo” as a choice in corn snake traits. Halo is accepted as an incomplete dominant trait. Currently there are “Halo” and “Super Halo” options. I understand that ordinarily, with an incomplete dominant trait, either an animal displays said trait or it isn’t carrying the trait. Halo is an exception in that, almost without exception, it is only visible in combination with amelanism. Non-amel morphs may have the gene but not show it. This info could be helpful for family trees and for breeding projects.

By way of example, I had a 2022 clutch from a Xanthic Halo Snow het Caramel, Stripe (Sunlight) & a Caramel Ghost Stripe het Amel (Odin). The Snow offspring are developing Halo coloration. I have no idea if the Caramel Ghost Stripe, the Anery Caramel Stripe, or the Anery Caramel are also Halo. It would be nice if I could tag the non-amel babies as “Pos Halo.” And nice if I could search for these.

I don’t know how feasible this change is. It may not be workable because it would be too complex for the calculator. In any case, thanks for the consideration. :slightly_smiling_face:


I’d love the same option for Palmetto. At least to my inexperienced eye, identifying het Palmetto in non-normals seems to be nearly impossible.

Plus, shouldn’t homozygous Halo be labeled green blotch instead of super Halo? I’m not super well-versed with Halo, but I thought that was what Sarah Mohr discovered.


I agree, this could be useful with Palmetto, too. Good suggestion.

You’re correct. Homozygous Halo is customarily called Green Blotch rather than Super Halo. It works just fine for the calculator and search functions as Super Halo, of course. I just mentally make the terminology switch, buuut… It would be nice to have that correction, too. While we’re on the Halo topic. If that’s not asking too much. Please. :grin:


I’ve added this change to the list :blush:

This is the same issue as Palmetto as Olivia notes, and I’m not sure there is a way to work it into the calculator… I guess @owalreptiles would have a better idea of the possibility though.

The right thing to do for the time being though would be, not to use the Halo tag for animals you can’t guarantee, but mention in the description that it is a Pos Halo.


Hooray for Green Blotch! Thanks!

Of course! That’s what’s I am doing. It’s a reasonable workaround. I miss the “Pos Halo” more in the search function. Here’s a thought, though again I don’t know if it’s feasible since I don’t know anything about programming. Would it be possible to list Pos Halo and Pos Palmetto tags in the search function only? Could be an asterisk explaining why these traits couldn’t used in the genetic calculations?


Erm… I dont know. That seems reasonable… I’ll discuss this with the team during the next up update and see what we can work out.


Thank you for checking on it. Either way it shakes out, the exploration of the possibility is appreciated! :clap:


I dont know corns at all. So Halo in the heterozygous is not visual? But is visual in the Homozygous? Also visual in the heterozygous in certain combos? Sounds like pied in ball pythons, but we call it recessive. Then you would have the ability to search 50% pos hets as well.

or what am I missing?


I don’t know corns either, but sounds similar to me as well to how we treat pied.

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Your description is exactly correct for a recessive trait.
Halo is not recessive, however. Its mode of inheritance is known as incomplete dominance. It is visible in heterozygous animals as well as homozygous animals. Its expression is different in heterozygous animals as compared to homozygous. In heterozygous form, it’s just called Halo. It affects the corn snake’s “trim;” yellow saddle borders, belly checkers, edges of side markings. The homozygous form is called Green Blotch, and the coloration fills the saddles and side markings. It’s also often a different shade from the homozygous Halo. That’s all normal, straightforward incomplete dominant stuff.

The part which makes Halo different is that it’s essentially only visible in Amel-based morphs. Amels and Snows are the usual visible Halo animals. There have been, I believe, some Halo Blizzards and other things. Sarah Mohr-Strahley described a hypo youngster who showed Halo for a short while. It isn’t that Halo is linked to Amel: it’s not. It’s just that Halo is covered up unless Amel is also present.

If a snake has the Halo gene but not the Amel gene, the Halo coloring is masked by melanin. It doesn’t show. At all. The snake can pass the gene to offspring just the same as a visual Halo, but there is simply no way to look at it and know it’s got Halo. That is the reason I requested “Pos Halo.”

The Morphpedia has a great write-up for Halo.


I think that Matts thought here are actually quite good…

Het Pied can be seen visually in some combos, as Halo can be in Amel combos.

If made recessive then Halo can still be the name for the het and Green Blotch for the homo… no need to add a “het halo”.

Then we can add combo names of “Visual Halo” for Halo + Amel morphs? That way we have the pos hets…


Sorry I can see your replying, Caryl… I just wanted to add.

We can explain in the Morphpedia why it is set as a recessive vs an incdom trait to clear things up knowledge-wise, but I think this is the best way to work this in calculations.


Hmmm. I’ll apologize in advance if this reply is a bit fuzzy. Having a bit of a rough day.

I believe I understand the intent here. And I can see where it would be functional for one generation. But after that, calculations would be botched. Maybe I’m confused and missing something, but let me try and show what I mean. For shorthand I’m going to use R = recessive mode of inheritance and ID = incomplete dominant mode of inheritance.

If a gene is ID and one parent has it, 50% of offspring have and express it. (It can be seen on the MM calculator with something like using the more typically presenting Red Factor as an example since Halo’s unusual visual presentation is the point of this discussion and it doesn’t appear accurately on the MM calculator.)

P1 heterozygous form ID trait x normal: F1 results, 50% of offspring carry and visibly express trait, the other 50% don’t have it at all.

F1, heterozygous form ID trait x same: F2 results,75% have visible trait (25% super form, 50% het form), 25% haven’t got it at all.

These results are very different when we use a recessive trait in the calculations. Here’s an example with Caramel.

P1, homozygous Caramel recessive trait x normal: F1s 100% het Caramel, none visible. Hets are visible with ID traits so 100% would visibly express the trait.

F1 het Caramel x same: F2 results 25% visible homozygous Caramel, 50% het Caramel (which is invisible), 25% normal. With an ID trait, 75% would have the trait visibly expressed.

I do think I see what’s meant here. I’m just not seeing it as the solution. I’ll sit down with some Punnett squares and play with the “Visual” idea but I’m currently not seeing it working. May be just me.

There’s also the fact that the MM community strives to be an accurate resource. It is accepted in the corn snake community that Halo is an incomplete dominant trait. It’s been proven multiple times.

I wouldn’t want us to present any gene with inaccurate info about mode of inheritance.


Apologies, Thomas. I didn’t see this before. Yes, I agree that explaining the settings in the Morphpedia could take care of the confusion.

I am still not seeing it as an answer in the calculations, though. I’ll play with it later tonight and maybe it will bang me upside the head. :bulb:
Thanks for the ideas!


I see two problems. One is trying to fit all phenotypes into neat little boxes. The calculation doesn’t change, as all genes are calculated the same. its all just heterozygous and homozygous, then the hobby gives names to them. In the bp community we take it a step further and just say if you can’t normally see the heterozygous visually, its recessive, then pos hets work for hobby purposes also. which seems to be what you want to search for (possible halos)

het pied x het pied = 25% pied, 66% pos hets
halo x halo = 25% super halo, 66% pos halos

sure when you have other genes in the mix the heterozygous can show through. It’s not just pieds, there’s clown, hypo, and albino, I can show right in my own collection and I’m sure there’s more. Also The more of these triple and quad het animals that are being made now a days and defiantly not looking normal, we wouldn’t really be able to call much recessive if we went that route. So that’s where I think the other problem is the corn snake community seems to be classifying things different than the bp community. If I’m understanding everything correctly.


In my opinion, I’d be fine with both Halo/Green Blotch and Palmetto being categorized as recessive but with an information note similar to those for morph issues, that says they’re classified as such due to masking of the visual het forms by other genes. That satisfies all the classification issues, and the calculator isn’t really that big of a problem, either, if you think about it.

I do know that especially with Palmetto, a lot of breeders I talked to weren’t fond of the switch when it went to inc-dom, because that meant calling what used to be just Palmetto a ‘Super Palmetto’ and the het a Palmetto, while removing the ability to label animals that couldn’t be 100% confirmed but came from lineage that could prove out. It also undermines the naming and especially the understanding of the morph to suddenly bestow the name for the homozygous expression onto the heterozygous. Much like a “Super Halo” is actually a Green Blotch, a het Palmetto is not a Palmetto. A Palmetto is specifically the white snake with splotches of color.


It seems to me like it solves all website related issues without changing any thing else besides morphpedia information, is that correct? There’s also the social part of reclassifying things and hobby never seems to take well to that. Tho it sounds like you guys had something similar with the Palmetto, is it in the same boat as it would possibly benefit from a recessive classification for search and calc reasons? I apologize I strictly breed ball pythons so I’m just trying to understand based off this thread alone.

So what where the benefits of the switch, is i just technical accuracy? Even the above scenario I’m not familiar with technical definitions to know why it would be inc-dom or recessive. i always have to ask @t_h_wyman about things like that. It just seems like recessive classification would satisfy the search/calc part of it.

I appreciate your explanation, this has me pretty curious now. Though at first I was literally this guy:


I do not know anything about Halo so I cannot ante in there. But Palmetto is inc-dom, not recessive, The fact that it is sometimes masked by other morphs making it difficult to ID does NOT change that fact. We are not relabeling YB in balls as recessive because it is sometimes masked in complex combos. I can also point to cases where Spider is masked in complex combos (not including Blackhead), and we are not going to suddenly change it to recessive to account for that.

The purpose of Morphpedia and the calculators and the listings is to reflect the true and accurate nature of the morph. The goal is not to just cater to the “easy way of doing things”


A post was merged into an existing topic: Palmetto is Incomplete Dominant [DONE]

so here my question without other mutations, YB is visual. without other mutations, het albino is not visual. however with the right combos, YB can become not visual or het albino can become visual. (I know het pied is the favorite example but I have glaring examples of het albino in my own collection) So what makes one what classification? I always had the thought of comparing a mutation to the WT version and generally thats how it seems to be classified, tho im aware that doesn’t mean its technically correct.

Their above issue, with the search and calc, it seems to be solved by at least treating it in the system as recessive, as in our system we only have recessives getting the pos hets option for search and calc output, which if im understanding correctly the calc would have more accurate output. So should we talk to thomas and john about treating it as recessive with a inc-dom label slapped over it?