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TadStone's avatar

My Little Pony: Genetics

For once I wanted to do something really nerdy.
Warning: Science with My Little Pony ahead!

If you find any mistakes please feel free to post them or to send me a message.

Links to the other theories (just to give full information, not to discredit them in any way!):

My Little Pony is owned by Hasbro.
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EDIT: Added a very small part about Alicorns.
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spelux's avatar
You lost me at allels i shouldve listened more carefully at biology class
princesschickeeens's avatar
Well the horn will be poking out so *huge gasp*
If rarity produces a child it would be a earth pony since
(Hopefully im right)
Her dad is a earth pony
KikyoTheFluffyFox's avatar
I need help. I have a male unicorn and a female earth pony. what offspring would that make?
BlurbOctopus's avatar
I need that too. Trenderhoof x Applejack
SketchyKohaiDraws's avatar
What would come out if the parents were a pegasus and a unicorn? Which gene is the strongest?
xxSimu's avatar
judging from theory 2 earth ponies have capital letter genes, which usually means dominant genes, whilst unicorns seem to have recessive genes.

it really depends in 4 offspring there should be an Eu EE uu and a uE which is usually how genetic formations work i think. so it really depends but the offspring is most likely to be an earth pony because of the dominance i suppose, but you could probably get anything lol. flip a coin.

if somewhere in a bloodline there was a pegasi there's a chance the offspring could be a pegasus, since the parent can be a carrier of the pegasus gene although it's quite recessive.
Hawkflight-FAX's avatar
I know this theory is really old, and while it does still hold up remarkably well, I do have a question. All of this seems to be forgetting that earth ponies are a distinct race, with abilities that none of the other races seem to express. Hoe does this theory account for that? Do the unicorn and pegasus genes also act as blockers for earth pony magic? Thus making it a trait that in theory all three races could possess if the other two didn't block the ability? Or, what if there was a third gene controlling the expression of earth pony traits?
MyLovelyJacksonForev's avatar
Ugh, I remember how complicated it was to study this in science a few years ago. What if the mother is a Pegasus and the father is an Earth Pony? What would the foal be?
Hawkflight-FAX's avatar
Well, let's see. The dad's possible genes are as follows:
  1. PPUU
  2. PpUU
  3. PPUu
  4. PpUu
And the mom's possible genes are:
  1. ppUU
  2. ppUu
  3. ppuu
Therefore, the possible outcomes are:
  1. PPUU
  2. PPUu
  3. PPuu
  4. PpUU
  5. PpUu
  6. Ppuu
  7. ppUU
  8. ppUu
If we refer to the chart above, we get the following possible outcomes:
  1. Earth Pony
  2. Earth Pony
  3. Unicorn
  4. Earth Pony
  5. Earth Pony
  6. Unicorn
  7. Pegasus
  8. Pegasus
So, yeah. I could be mistaken, but it looks like that combination of parents could yield any of the three races.
Layla-Nightingale's avatar
Um... sorry, but I don't quite get this. Can ya help, please?
If we're havin' a Unicorn mom an' an Earth pony dad... 
MrHaziq's avatar
Depends on the genetics of the mom and dad. I can't make a chart, but I'll try my best using their theory as a base.

The dad's possible genes are;
  1. PPUU
  2. PpUU
  3. PPUu
  4. PpUu
The mom's possible genes are;
  1. PPuu
  2. Ppuu
I'd go deeper, but first, which gene does the mother and father have?
anoneemoos's avatar
Mendell's work there. Nice one on doing homework on your biology class.
I have this theory, see what you think of it. Based on the Hearth's Warming Eve episode, it is very much like yours, but adds a bit of info. At the beginning the three races didn't intermingle. They happened to be pure breeds, in the sense that all Earth Ponies were UUPP, all Unicorns were uuPP, and all Pegasi where UUpp. In that situation, even when the different types of ponies learnt to cooperate and be friends, it is possible that mating between them was still generally not contemplated until later.

The main difference here is that all uupp are (potential) Alicorns. I think Alicorns won't express both wings and horn at birth, even when they are uupp. What they express at birth may be based on further genes, but there is too little info to build a sound theory around that. Maybe they need to do something big to get to express those extras, even though in Magical Mystery Cure it seems to be Princess Celestia who does it. Princess Cadence is said to have been born a Pegasus before becoming an Alicorn.

Now, How does fit canon? Shining Armor is either uuPP or uuPp (or potentially an uupp that hasn't gotten to express wings. For all we know it might be pretty rare). Princess Twilight Sparkle is obviously uupp. This is compatible with Unicorn parents, both of them have to be carriers of the Pegasus gene. The Cakes have to be both UuPp, leading to having a child with uu and a child with pp. The Apples seem to be a very traditional family, so they might be pure, as seems the case with the Pies (traditional if we discount Pinkie). This would also support the far cousins theory. Cloudsdale Pegasi can be pure and all foals born there will be Pegasi. If someone wants to mate with a non-Pegasus, they will have to leave Cloudsdale to meet a suitable mate in the first place, so no big deal.

So, what do you think? :)
Donttouchmykitty's avatar
Thank you so much for making this! You are awesome. I love the way you think. I totally agree with your theory. I was wondering though ... How would sea ponies and maybe even bat-ponies fit into this? I know sea ponies have yet to be seen in Equestria and bat ponies were an accidental creation. What if though a bat pony were to produce offspring with another pony? Would the bat pony have bat pony genes to pass on or is bat-pony-ness just some kind of illness created by magic that is not inherited? Also, (as if this isn't a lot already LOL) what about donkeys? I know Matilda and Cranky get married. What if a donkey would try to produce offspring with a pony? Would the result be a mule, like in reality? Here is a link to MLP WIKI. It has mules and donkeys on the page if you need more info on them. I hope I'm not being a pest. It's just genetics is so fascinating to me and I love My Little Pony. I would just love your take on all this! You seem like you would have a very logical and intelligent answer! Thank you for your time.
OolimenoteoO's avatar
them brony haters will look at this and say wtf
NicLove's avatar
p.s. your "pp uu" isn't a pegasus ! it a fling-unicorn !
OlympeMaxime8875's avatar
Actually, since the pp (pegasus) genes overwrite the uu (unicorn) genes, it's safe to say it would be a pegasus. 
NicLove's avatar
ok. but how do you get a Alicorn/PegaCorn ?
OlympeMaxime8875's avatar
(don't take my word for this, I'm only basing this off the little I've learned from the post. I suck with this subject.)
OlympeMaxime8875's avatar
Either magic in their genes, or a gene that stops the pegasus genetics from blocking out the unicorn ones.
Rainseed's avatar
You're well versed in the mechanics of genetics and was wondering what your opinion is on this theory:
Many people enjoy it as it addresses winged unicorn genes in an approachable way, I myself included, but would like to get your opinion on it before using it for further reference (solely because of its explanation of winged unicorns) as you are talented in this field<3
TadStone's avatar
hmm, I am actually not sure about this one
don't get me wrong, it does work in itself but it does not feel right

The biggest flaw is the very low frequency of the a (alicorn) allel. Basically, this means we have a highly positive allel that is nearly non-existant in the population. Such a distribution does not sound evolutionary stable to me at all. Either there are mayor drawbacks to that allel or it should be present in large part of the population, at least given time (and we had some time since Celestia exists and with her the gene!). The alicorn gene is more on the level of a negative genetic disorder than a positive effect.

This is especially true, since the theory set there to be 0.57% winged unicorns. This is set way to high. Given a pony population if merely 1 million, there would be over 5700 winged alicorn around already. So the allel must be even more rare.

Let's say the equilibrium really is as such (and the allel is therefore not that positive after all), there would be a good change of it dying out by change even.

Please don't qoute me on this one. I did NOT write out the differential equations to calculate all scenarious through. It just feels weird from experience.

Also, the whole Twi ascension kinda takes the need out of a special alicorn gene. Just my first impression.
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