Twin Ball Python Questions

I bought a lovely pair of twins last year and have since gotten curious about how twinning works in Ball Pythons. Does anyone here know what the odds are of getting twins in BPs? I’ve also noticed that a lot of twins seem to have the same set of morphs, but not always. What’s that about? What exactly is going on genetically with these twins? My understanding of genetics is still fairly limited, but I would have guessed that twins with the same set of morphs would usually be identical twins. However, my twins certainly aren’t identical - their markings are different, and one is a male and the other a female.

Just curious if anyone could shed some light on the science behind all of this for me!

Here’s a cute photo of my little ones.


Oh my goodness they do look quite similar! And very pretty! I can’t help you with your questions but you will definitely get answers/opinions from others who have knowledge about this.

All the best to you! :snake::frog::lizard::blush:


I wonder if @t_h_wyman might not have some knowledge in this area to share?


I do know that years ago breeders would try to find twin bps in the hopes that they had a tendency to produce more twins. There reasoning was bps lay small clutches so more babies per egg would increase their chances of making more of whatever morph they were after. I do not know for sure if this is factual, just what I’ve heard.


What cuties! I can’t give you BP-specific answers as far as odds of twinning, or of fraternal vs identical twinning. I can, however, answer some of your other questions as the answers are true across species.

Twins who are identical are produced by a single egg fertilized by a single sperm cell. At some point very early in development, the cluster of undifferentiated cells which was the snake-to-be separated into two clusters. The reasons why this sometimes occurs are not (to my knowledge) fully understood. Each of these tiny clusters went on dividing and eventually became two individual baby snakes, each of whom had the same genetics because they originated from the same fertilized egg. They have the same morphs, the same sex, the same hets.

Fraternal twins result from two egg cells, each fertilized by a different sperm cell. These twins have completely separate genetic information, thus may be of different morphs and/or sex, and carry different hets. They’re neither more nor less genetically related than are any other siblings.
Edit: For the snakes, they somehow were encapsulated by a single eggshell, developing and hatching as twins. My guess is that this situation is similar to what’s seen in human twins who share an amniotic sac. This doesn’t occur with all multiples; sometimes they share amniotic/chorionic membranes, and/or placental structures. Sometimes each fetus has its own completely individual in-utero support system.

I’m a corn snake person, but I’ve run across curiosity on this topic in corns. I personally have a female (Victory) who is a twin. She produced twins herself this past season. That’s just one anecdotal snippet and certainly not scientific proof. That said, the tendency to produce fraternal twins is known to be higher in family lines for some mammals (including humans). Interestingly, for humans at least, the frequency of identical twinning does not appear to be linked to family fertility. It seems to be evenly distributed.

Hope that helps.


Thank you all for your comments! And Caryl, I really appreciate you taking the time to explain some of the ins and outs of twinning to me. This really is a fascinating subject.

I was looking at some other threads on twins before I started this one, and I saw a couple of comments mentioning personal experience with getting more twins from certain lines, so that does seem likely, especially since your own experience suggests the same. Maybe I will have some more twins in my future, if that’s the case!! How exciting.

I didn’t know that identical twins were an exception to the whole twins running in the family thing - that’s very interesting! So a genetic tendency for high twin rates only applies to fraternal twins? I wonder why?

I would still love to know if anyone has calculated the odds for BP twins in general, if someone else comes across this thread and has info on that.

Also, the whole thing about twins having the same morphs but not being identical… if mine are indeed fraternal twins, and they both share the same exact (five!) morphs, that seems like it would be extremely rare. But it seems like a lot of BP twins are the same morphs, which I still find very odd. Why would that be common in non-identical twins? If I picked two eggs at random, it would be pretty unlikely for both babies to hatch out with an identical morph combo, especially with pairings that have more morphs at play. Just seems… weird, doesn’t it?

Man, there is so much to learn about these animals! I love it!

Sorry if any of this didn’t quite make sense. It’s late for me and I’m having trouble formulating good sentences. :rofl:

Thanks again everyone for your comments. Here’s a fun picture I took of my twins for Halloween, just for the heck of it!


How sure are you on the gender identification? For $26 each you can have them genetically sexed.

If they are different genders it was just luck that the same morph.

Of course even if the same gender doesn’t prove identical twins but with the long odds of the same morph combo it seems likely.

My first ball python clutch in 2000 had twin normal males. The mom and non-twin sisters were the foundation of most of my projects through 2020. Unfortunately I haven’t kept much for records but seems like my small operation of 2 to 13 clutches a year was producing twins every 2 or 3 years.

By the late 201Xs I finally started producing enough visual morphs to notice that not only did my twins happen to be the same gender they were also the same morph making me suspect they are identical and not fraternal twins.

2020 was an unusual twin year even for me. I ended up with 4 sets of twins out of less than 16 clutches (only about half from the twinning line).

Unfortunately I gave away most of my twin line in 2020 as I had a bunch of holdbacks from other lines to make room for. I did keep one pair of GHI female twins. Hopefully one or both will lay this year.


Oh wow, how interesting!!! It does sound like you had an unusually high twinning rate. That’s at least… four people, I think, that I’ve come across who have experienced higher twinning odds in certain lines. That can’t just be a coincidence, right? Something must be going on there. Fascinating!

Any advice on special care for twin BP hatchlings, since you’re fairly experienced with it? I have heard that some might need a little extra TLC to get going and I want to be prepared, since we may very well have good chances for twins from these two.

Can I also ask - on your same gender/same morph combo twins, are their patterns also the same, or are there subtle differences? The breeder we got ours from popped them for us at the show as a sort of proof of genders… he seemed pretty certain about the female, but he told us that he was not 100% sure on the male (maybe this was because the twins were still pretty small when we got them?) so it’s possible we have two females. I have been hesitant to learn to pop them myself because BPs seem so delicate and I’m afraid I might hurt them if I do it wrong. Although I will probably have to learn sooner or later if we want to do very much breeding in the future. :sweat_smile: That’s really cool you can send for a genetic gender test - maybe I will try that if I still can’t bring myself to learn the pop method.

Man, that would be awesome if they ended up both being girls! I mean, I’m perfectly happy with one of each also, but two girls would be even better!

I do want to point out that their patterning is different - I can easily tell them apart because one has three little lines along her spine right behind her head, and the other has only two there. I don’t know enough about identical twins though, to know whether a slight difference in pattern necessarily means they are not genetically identical. I have heard that some genes’ expressions can vary based on things outside the genetic code itself. I can’t remember what that is called, but maybe it’s a situation like that? Like maybe, just as a random example, temperature can toggle something in a gene to cause it to express differently. So if one baby was warmer it might not look exactly like its identical twin, even if all of their genes are exactly the same ones. Just a theory - I really have no idea.

I hope your GHI girls do lay eggs this year! That would be so awesome for you, and GHI is such a pretty morph, too. I recently discovered the GHI Black Head Hypo combo, and it looks soooo cool. And even better with Red Gene added in! My husband really loves the GHI Mojave Hypos. Just a great gene that looks cool with lots of other stuff!


Again I have to say, you sure know your stuff! :upside_down_face::wink::blush:


I had one ball python hatchling last year that I was unsure of gender. Was pretty sure it was a female and I was just seeing the scent glands inverting but maybe they were really small hemipenes so I sent a shed in and confirmed it was a girl.

I think the exact pattern in ball pythons is like fingerprints in humans. Human genetic identical twins have different fingerprints. There must be some randomness. Like they are rolling the same loaded die but two different rolls. My GHI twins have similar but different patterns. I’ll dig up a picture of them together.

I actually find twins a bit of a pain. These two hatched at 17 and 19 grams. I had to assist feed them for months. Sometimes twins do just fine but due to their small size they are more likely to be difficult.



They are beautiful!

I will have to research assist feeding, just in case. I have heard it mentioned a few times but never seen exactly how it’s done. Doesn’t sound fun, but you gotta do what you gotta do when you love your animals!


Oh my goodness, that Halloween picture is so adorable! Nice job with the pumpkin, first off. And the snakes are the icing on that cake, to mix my metaphors horribly. Lol


True. The fingerprints of identical twins are similar but not identical. Identicals aren’t truly identical. Some twins are closer to it than others, but no individual is exactly, precisely like any other. Which is rather fascinating, when you think about it.

Slight differences in pattern don’t mean they’re not genetically identical. There are always differences, as mentioned above. Sometimes they’re very subtle, sometimes they’re easier to see. The genes present in an individual are called its genotype. The visible expression of these genes is called the phenotype. Identical siblings have identical genotypes, but some differences in phenotype. And yes, there are known environmental causes for certain phenotypical expressions.

You have exactly the right idea. :wink:
And there’s a whole field of study called epigenetics which explores the relationships between genetic expression and the environment.


Your experience with twins is fascinating! I’m curious, did you do anything differently in your 2020 season? Different temps, different supplements for your females, different light exposure, anything you recall?


Mainly I just was able to get more females in my small collection to lay in 2020. A lot of years I only have 2 to 6 clutches. I only came to realize twins aren’t that common in most collections in the last few years. I think the rate I was seeing was always way more than normal, just partially lucky in 2020.

Really wishing I had kept actual records. Other than the GHI twins and a pastel GHI sister of theirs I have some other females descendant from the mom of the original 2000 clutch but I can’t be sure if any of those lines have recently had twins. I know I didn’t keep any of the 2020 twin moms. The remaining females may well have lost the apparent gene for cells that don’t stick together well enough.

I also haven’t kept males much as I’m usually buying males to get new genes so I don’t really know that it couldn’t have been passed through males, it just worked out that I haven’t really tried. I try really hard to avoid any inbreeding so that is another reason I haven’t used many holdback males.


Very interesting. I wonder what was going on with your girls, especially in 2020 lol. ( BTW Fraternal twinning is the direct result of things that happen solely in a female’s reproductive tract. Males don’t affect this; their sperm is either available or not for fertilization and that’s it. That said, it makes sense to question if a male from a line with a higher incidence of multiples might sire females who are more likely to produce multiples. I think that jury is still out. :thinking:) I find the whole topic fascinating. I know, it shows. :laughing: :rofl:


I’m assuming mine are identical twins as have always been same morph combo since I started producing morph combos.

Maybe I’ll produce a male worth holding back from the twin line and I can breed him to one of my non twin lines (without inbreeding) and see if twins start popping up there. I’m assuming it’s a single dominant type gene and of course it’s pretty hit or miss so I might not want to dedicate enough breedings to see if the male got it.

It’s still happening rarely enough that I’ve never had two sets of twins in the same clutch. Really should start keeping records as not even sure same female has produced multiple sets over a maybe 6 clutch tenure.

So many visual projects to catch up on not sure it will work out that I can dedicate many breedings to a twin project that frankly is a bit of a pain when it happens due to extra small babies.

One of the GHI twins is being paired with a mahogany likely het pied as is her pastel GHI sister. The other with a chocolate het hypo ph desert ghost. I do need a holdback male GHI mahogany and a chocolate het desert ghost so if a nice enough one of either hatches I can keep him. But unless he just happens to be a twin no telling if he got the gene.


I suspect that the tendency to produce multiples is more complex than a single gene. If it weren’t, I think it would be much more common than it is. I feel your pain, for sure. There are always more projects and potential projects in my head than I can possibly find hours or space to do. :snake: :heart:

If you do hang onto a male, I’d be interested to see what happens with his offspring. I’m doing that in my corn snake collection as well. I kept the 2022 male twin produced by my twin female. Got a couple of female holdbacks from that clutch, too. We’ll see what happens.


I’m just basing the single gene idea on how resilient it has been in my collection without inbreeding. The GHI twins are great granddaughters of the mom from my original 2000 twin clutch. One of the 2020 moms was from that 2000 clutch but the other three were also around the 3rd generation or so. I do have quite a few other granddaughters and great granddaughters still but thinking they may be from branches that have lost the twin gene. Will try to keep better track of it going forward.