Genetics Overhaul Collection: Main Mod (Preview)
09.10.2026 UPDATE: Added the Spanish, Portuguese Brazilian and French translation links
29.09.2026 UPDATE: The newest mod version is 1.5, read about the update and download HERE, don't forget to delete old files (settings are fine) and reinstall the mod!
Finally I made one of the most challenging and wanted projects I planned to release. This mod collection provides completely another genetics system.
The main module adds essential genetics features we so missed in the TS4!
Inheritance from Grandparents
If you didn't know, the game completely ignores the appearance of grandparents. If you ever had an offspring with hair color or presets that reminded a grandparent, it was either a bug or a coincidence.
But this module is another story.
With a predefined chance (by default it's 80% but you can change it) an offspring inherits the parent appearance. It includes a skin tone, voice, face and body presets, sliders values, an occult race (if they have any) and hair and eye color. The remained chance applies on the grandparents appearance (by default 10% per grandparent).
So, this feature makes the offspring genetics way more interesting and diverse.
Smart Sculpts and Sliders Inheritance
The mod forces the game to apply the sliders which are related to the inherited sculpt from the same source (i.e. nose sliders from parent with parent's nose inheritance).
What about CC Sliders?
The mod recognizes hundreds of custom sliders! I took them from this master list (huge thanks to the author!). It means, that the algorithm will check which region of body / face a slider belong to, and will be inherited with other sliders of the same region. If the slider has opposite gender variant, it will be considered too. Otherwise, it will be inherited only if a child has appropriate gender.
Some of the sliders are inherited random such as height ones, because they don't actually belong to lower leg or neck. Yup, I manually checked every slider, and don't forget, that almost every slider package has more than one slider! I spent two days on it
So, please, just check this list if you're not sure whether or not my mod supports this slider. I hope you understand that it will be impossible for me checking every slider constantly.
Other CC sliders still work fine, they just will be inherited randomly.
I won't update the mod just for one more slider, because it takes lots of effort and time. Consider it too, please
And keep in mind, that I don't guarantee that one or another slider works correctly, I'm not their creator. I just add support, that's all.
What about CC Presets?
It's another story, as the game itself doesn't include them into the genetics, as the presets map of age and gender doesn't contain information about CC presets. Though, I'm investigating, can it be solved by manual mapping or not.
Natural Hair and Eye Color
It's so annoying that we don't have any possibility to 'dye' hair or make Sims wear colored contact lenses because the game percepts it as a change of genetics.
This module lets you to assign the natural hair and eye color, so you can freely change the Sim appearance and it won't affect the offspring genetics. Instead, the algorithm looks for flags of natural hair and eye color.
How does it work?
On the game launch the mod looks for player Sims and checks the hair color tags and the eye color values on their appearance and assign corresponding traits.
Regarding hair color, the highest priority have hairstyle and eyebrows. If the mod doesn't find appropriate tags (i.e. your Sim doesn't have hairstyle and eyebrows), it will look for a body hair color. It also works with CC as well until they have proper tags.
But no worries even if the mod didn't find anything appropriate (say, you use non default CC eyes) or you think a Sim has actually another natural color. With testingcheats enabled, Shift + click on the Sim and choose the correct color from the 'Choose Eye Color' or the 'Choose Hair Color' interactions of the Genetics Overhaul category.
Unnatural Hair Colors
Only teens and older may have unnatural hair color, that's why children have, for example, red hairs until they age up and get pink hairs. It works good in the vanilla, but if you have the Unnatural Hair Colors for Little Sims by SnarkyWitch, the mod will apply the unnatural hair color right from the infant age.
Eye Color Cheat Specifics
Because of great amount of eye colors (68 at this moment!), I divided it into categories by occult race. Yup, we now can assign any eye color regardless if a Sim is Human or, say, Vampire, but still it has the most appropriate occult race.
If you play without any occults, just check the first group of colors.
Otherwise, you can find a desired eye color in Vampire, or Mermaid, or Alien category and etc, if you have a corresponding game pack.
Please note that the occult eyes have quite extraordinary official names and I did my best to adapt it so you can understand more easily how do they look. But still, pay attention to the icon first. All of them come from CAS swatches.
Occult Eyes Fix
If you play with occults, you might notice that an offspring often inherits random eye color instead of the parent' ones. That happens because most of the occult eyes don't have a unique tag (just an occult race), so the game assigns random occult color.
But the mod memorizes the eye color ID instead of the tag and applies the corresponding eye color trait when creating an offspring. That's why a child will have exact eye color instead of the random one.
There is a special case for a few occult eye colors: they don't have a child version, they are for teens and older. The game just assigned them a brown color, but I mapped them to have a child similar color. For example, children with Blue Ghost fairy eyes have blue eyes until they age up.
Even if something went wrong and the mod hasn't replaced eye color on aging itself, you can use the 'Force Update Eye Color' cheat. It's available for teens and older who have these specific eye colors.
Occult Mutations
It's turned off by default, but when this feature is active, there is a chance (you can set it up) that a child will inherit a different occult race rather their parents and grandparents have, even if they aren't occults.
Adjusting Settings
Starting from the 1.1 version, you can adjust the settings directly in the game, just Shift + click on a Sim and choose the Genetics Overhaul Settings interaction. You'll see this menu:
The Reset to default option return these settings:
Do not inherit grandparents presets
Chance of Inheritance from Parent: 80%
Occult mutations are turned off
Inherit Grandparents Presets
This feature is turned off by default in case you want more fixed and predictable inherited presets. If you set true instead false, then the grandparents presets will be considered too.
Chance of Inheritance from Parent
The setting indicates possibility to inherit from parent instead of grandparents. This value should be between 0 and 1 inclusive. The grandparent inheritance possibility then (1 - inheritance_from_parent) / 2, or 10% per grandparent by default.
Also, the chance is applied on each genetics attribute separately. So an offspring may have eye color and nose from a grandmother, hair color and voice from a grandfather and other things from a parent.
If a parent doesn't have parents, then, naturally, only the parent genetics will be applied. If they have only one parent, the script will consider the parent genetics with the same chance (80% by default), and the grandparent genetics with 1 - inheritance_from_parent chance (20% by default).
Mutation Chances
Choose the Occult Mutations option and you'll see this menu:
There will be settings only for those occult types which game packs you have for.
All mutations are turned off by default, but you can set a value between 0 and 1 inclusive for any occult race you want. Please note, these chances don't affect possibility to inherit occult race that parents or grandparents have, only inheriting occult races they don't have.
What does the last setting mean? it's a possibility of an offspring becoming a random occult from non occult, considering all chances above. Say, you set a spellcaster mutation chance to 10%. It means that with 10% chance a fairy offspring will become a spellcaster instead. Yet, if the chance of mutation from non occult is 0, there is no chance to become a spellcaster, if it's a non occult offspring.
I haven't included ghosts and aliens, because it seems weird for me. Aliens can only come from Sixam, and ghosts are dead Sims with a soul basically.
It also supports a hybrid system if you have a mod for that. Then each inherited trait can be mutated (i.e. two traits can change instead of one).
Recreate Offspring
Starting from the 1.1 version, a report is generated for each born Sim (including NPCs and pets), you can find them in the reports subfolder:
Do not change anything in the file names or content!
The reports are generated for two reasons. First, you can send it to me if something went wrong when a Sim was born. Second, the data from these reports can be used to recreate an offspring.
What does it mean?
Say, you faced an issue with my mod and a born Sim is somehow buggy. It would be a disappointment to just delete this Sim and start everything over.
Instead, you can use the 'Recreate Offspring' cheat on the mother of this offspring (in general, on a parent which can be impregnated). Shift + click on the parent, and then select another parent. In this dialog you'll see only acquaintances of the same species of the first parent, which can impregnate (if that's a dog or cat. they also must be not neutered).
If these parents have an offspring with the mod report, you can choose the data of this offspring.
Right after that, the parent will be in labor and will give a birth to a new Sim. This one will have the same predefined data as the selected offspring has. But this Sim won't get their own report, because it will be an endless loop of the reports with the identical data. And it's just meaningless, as this Sim is generated by the EA mechanics. The original offspring won't be deleted automatically, so if you want it, do it manually (i.e. using the MCCC cheats).
If the selected Sims don't have children with the reports, you won't be able to choose anyone.
The cheat is available:
on not pregnant humans which can be impregnated or on female pets (if that's a cat or dog, they also must not be neutered) of the active household
this Sim must be on home lot, since they can't give a birth on other lots
the household size must be 7 at most (you need an extra space for a new offspring)
In any case, I advise you to make a save copy right before your Sim giving a birth with my custom genetics algorithm.
Compatibility
The mod is compatible with Wonderful / Wicked Whims (18+) by Turbodriver, Relationship & Pregnancy Overhaul by Lumpinou, Realistic Childbirth by Pandasama, NPC Family Genetics Fix by deadlystringnyc (it just doesn't use my enhanced genetics yet, but we're about to make a version to support my mod), occult hybrid mods. pregnancy interaction mods and so on.
Actually, I haven't found any conflicting mod yet, but feel free to ask me about compatibility with a specific mod.
It's compatible with MCCC by Deaderpool too, you just need to turn off a couple of features, because they don't support grandparents' genetics. Click on the Computer and open the MCCC menu. Then CAS -> Offspring:
Disable Use Parent Physical Attributes and Use Parent Skintones
Other appearance related things work without conflicts.
Also, my mod supports Genetic Unnatural Hair Colours for Little Sims by SnarkyWitch , so your infants will have unnatural hair color too with this mod.
Limitations
First of all, the mod doesn't affect offspring creation in CAS, because the CAS code is unavailable to see and be modify.
The mod mechanics are ignored when Wicked Whims adds a dead offspring to the family. But I don't think it's something important.
When a Sim becomes infant, it has the hard coded hairstyle. I made it to ensure the hair color will be applied correctly. I also don't think it's a big problem, you can change it later.
If you use a non default eye color, it may be skipped by the mod when assigning the eye color trait.
If the CC hairstyle doesn't have proper color tags (happens when a creator makes all swatches based on the black ea swatch), the mod looks for tags on the eyebrows, and after that on body hair. Keep that in mind and don't be surprised if you see black hair color on white haired Sims. Just set the traits manually.
CC presets are ignored, and not only by the mod, but by the game itself, because they don't exist in the special presets map that is used on genetics applying. I advise you to not use custom presets on Sims you want to have children. Or be ready to fix the offspring face in CAS.
The attraction system from Lovestruck ignores the natural eye and hair colors, but I think it makes sense, since Sims should be attracted or repelled by the current appearance, not by the biological one.
The mod works with pets too, but they don't have natural color system, because it's made different.
I can't think of other limitations, but you can ask me anyway.
Check the compatibility status HERE
REQUIRED
Base Game compatible
CONFLICTS
Read the compatibility section
TRANSLATION
Russian by me
French translation link by Hope
French translation link by ElianasDiaries
Brazilian Portuguese link by Jezzamia
Spanish translation link by JA Simmer
FAQ
No interactions?
You haven't installed Lot51 Core Library correctly
You haven't enabled testingcheats
How to set / reset the settings?
Read the Adjusting Settings section
The settings have been reset?
You inputted incorrect value somewhere, read the adjusting setting section
Regarding other questions, first read the compatibility and limitations sections, and other feature related sections
How to recreate a child if something went wrong?
Read the Recreate Offspring section
No Recreate Offspring cheat?
You haven't installed Lot51 Core Library correctly
You haven't enabled testingcheats
You click on a Sim from not active household, or they can't be impregnated (CAS setting, already pregnant, neutered in case of cats and dogs, not enough free slots in this household)
For more details, read the corresponding section
Does it work with CC sliders?
Yes, read the 'What about CC Sliders?' section
Will I add Slider_Name into support?
I won't update the mod just for one more slider, because it takes lots of effort and time. Consider it, please
What about CC presets?
They are ignored by the game itself, not just by the mod, when genetics is applied
Is there a conflict with <Mod Name>?
Read the Compatibility section, and if I haven't mentioned this mod there, ask me
INSTALLATION
Put it in the Mods folder no deeper than one subfolder
Don't delete the JSON file, it has essential settings! And don't move it anywhere
The newest mod version is 1.5, remove all files and settings and reinstall the mod if you have the older version!
DOWNLOAD
Read about the update and download HERE (Public Access)
This is the most difficult thing I have ever made, so I'll be very grateful if you decide to support me 🙏
OTHER MODULES
All modules from this collection are independent and don't conflict with each other
Better Inheritance
No Weird Age Up and Random Genetics
P.S. I can only help if you provide me with the details of any issues you are experiencing. Read THIS before writing a bug report (via the link below, not in the comments section).
Contact me | Buy me a Coffee | Bug Report | Mod Status Sheet
Comments (74)
We desperately need a HORSE genetics version of this cause I HATE how the foals only inherit their coat color, as an exact copy, either from the sire (father) or dam (mother) and absolutely nothing else and it makes breeding horses so....boring. ;-;
I'm going to make more deep genetics for pets in the next update! But it will be a big help if you explain how really should it work as I'm not good at horse genetics (only the cats one lol)
Hi! I was hoping you could help me troubleshoot. I have lot 51 downloaded, all files are directly in the mods folder, testingcheats is activated, and the genetics category isn't an option when I shift click on my sim.
Hi! Does the game see lot51 library? You can find a log file of this library in the same folder where the script is located. I need this file's data to understand your situation better
Eliana's Diaries did a French translation if you want to link to it! It's on Curseforge. https://www.curseforge.com/sims4/translations/genetics-overhaul-collection-traduction-fr
Hello, here is my french translation, thank you for your work ! https://www.patreon.com/elianasdiaries/posts/traduction-de-de-170334443
Just so you know when a cc Creator makes hair yes, the tags can get screwed up if they make all of their hair swatches based off of the black hair swatch, but since I am a cc Creator and you are a mod maker, you are aware that CC creators can correctly tag their hair colors in the tagging categories in S4S. So put your foot down LOL and tell creators to just tag their hairs properly. It's lazy CC making when creators don't tag their content. I had to go through the entire thing and learn it properly when I wanted to upload my cc to The Sims resource many years ago, and I had to teach myself about tagging and categories. So don't take the responsibility off of CC creators to tag their shit properly LOL ᥫ᭡♡
You're actually right about that, I wish all creators learned fundamental basics as incorrect tagging leads to, at least, attraction system recognizing sim's appearance wrong. I had to set these tags manually for eyes and hairstyles I used lol Fortunately I'm using now only CC with proper tags. Thank you for being considerate about that! And yeah, if something is really good in TSR, it's their quality requirements
Hi! I’m getting a Last Exception that seems to indicate an incompatibility between Genetics Overhaul and Lumpinou’s RPO Module 13 (Miscarriage & Pregnancy Loss). When RPO tries to create the unborn Sim during a miscarriage, Genetics Overhaul throws: AttributeError: 'SimInfoBaseWrapper' object has no attribute 'genealogy' and this eventually leads to: AttributeError: 'NoneType' object has no attribute 'restore_parent' The traceback shows RPO’s miscarriage system calling unborn_create_sim_info -> apply_genetics -> Genetics Overhaul. Could this be a compatibility issue with Genetics Overhaul and RPO Module 13?
Hi, that's not a compatibility issue. Sometimes Sims temporarily lose the data, and in such cases my mod can't work. I know about this issue and it's fixed in the upcoming update. I hope to release it next week
Hi, sorry to bother but i would like to ask: i tried everything but every single kid thats born takes the dad's hair and the mom's eyes...never viceversa. Could you help??
Hi, that's a plain genetics random, it would go the same without my mod too as it doesn't apply any weights between parents. You can just set the max number of babies to 6 using MCCC and experiment
Thank you very much for this mod. I noticed that you locked in a hairstyle, and I am wondering if there is any way to disable this because it disables MCCC's randomize hair option on all sims, and I loading CAS for every sim takes forever due to the amount of CC I have. Thank you again!
Hi, I'm just curious (as well as for the other modules), will this work properly in pre-existing saves? I'm assuming yes, but I have to just ask before I add this in the game for my legacy gen save!
Hi I have been playing the mod and really like it, thank u. However, Children in my game often inherit the facial features just fine, but the hair and eye colour inheritence doesn't seem to work for me half the time. For example, two blonde haired, blue eyed people are often producing black haired and brown eyed children. The grandparents either don't have these colours or the sims don't have grandparents, so I don't know were these genetics are comming from. Seems to always default to some shade of brown eyes and black hair. Do u know what could be causing this? Could it be a conflict? I also changed the MCCC settings as u suggested. I just don't know why this is happening and why it sometimes applies the genetics but they sometimes change hair and eye colour when they grow up to black hair and brown eyes too. I only use the maxis hair colours and eyes.
Hi, several people and I confirmed that these issues happen starting from the 1.126 game patch even without any mods in the new save start CAS mode. Especially something changed in the non default eyes (for some reasons quite many of them are constantly switching), some hairstyles, including the vanilla ones, have a similar bug. I remember this bug was a year ago, but EA somehow fixed it. In the next update I'll force infants to have exact eyebrows to reduce possibility of switching hairstyles. However, I don't know, what exactly changed in the eye colors
Hi, the mod is not working for me and I was wondering if anyone could help me troubleshoot. I have Lot51 installed correctly. When I turn on testingcheats, I can adjust the mod's settings and change my sim's natural hair and eye color. However, even when I turn parental inheritance to 0, make all 4 grandparents have green eyes blonde hair, and both parents have black eyes black hair, all the babies are born with black eyes and black hair (full parental inheritance). I've tried changing the parental inheritance value a bunch, and no matter what I do, the newly born sims only ever have their parents hair and eye colors. Has anyone else run into this issue?
Hi, first of all, you should discuss it with me, as I'm the only one who knows how this mod works. Was a report generated after birth? If something goes wrong, my mod uses EA genetics, but it will be written in the report file. How deep you placed the mod? Which natural eye and hair color traits a child gets? You can check it in the sim panel
hello! thank you so much for making this mod, i really love it, except that i'm encountering an issue where i can't modify my sims in CAS after pressing play. the sims appears in CAS, but nothing else loads; genetics, hair, clothes, none of it, even the confirmation/exit button is missing.
Hi, that's definitely a UI issue, and my mod doesn't change anything in CAS. You should check it without mods and make 50/50
Thank you for the amazing mod. I have a question regarding the occult mutation setting. If I set the "Change of mutation from non occult" to e..g 1%, does this mean my offspring from non-occult sims could become a occult? I don't want my offspring from the same occult to randomly mutate to another occult, so I set all the other settings to 0 (spellcaster, vampire, mermaid etc.), but would only have the last setting active. Not quite sure if I understood the explanation above correctly :)
Hi! Thjs setting means that non occult offspring can get a mutation from ascendants. Say, both parents are plain humans. A child always will be a human too. But with specified chance a child can get an occult type just like their grandparent has. So, it's not about random mutation into an occult, but rather mutation from previous generation. However, I'm working on the update, which will allow to set chances of mutations into an occult regardless ascendants occult type
Ahh thank you so much for this mod, we have NEEDED a fix for this. Thank you for all the amazing mods over the years! 🩷
Thank you too! 💗
Hi, Thank you for this mod, I'm really excited to use it to it's full potential but I've hit a snag and it's having some problems with miscarriages. Can I send you the log?
Hi, yup, you can send me a link, it's better to DM so I won't miss it But what exactly was happened? And which mod do you use for miscarriages?
Hello ♡ My sims (infant and toddlers) always reset their eyes once they leave CAS still... But it's happening only with my rotation family as far as I noticed My fairy sim married Lou Howell and have 3 children: one toddler and two infants and they should have her eyes "Purple" the occult one but even with the trait and I changing it in the cas (I have MCCC cheats for always use Edit in CAS and Better Simology Panel which allows to change it throught there) they always got back to the same color as Lou But the toddler of my main family also has the same eyes and it doesn't change back
Hi, first of all, which mod version you have? Did you remove the old files? Second, which exact purple eyes do you mean? Cause there are quite plenty of them. You can write me its name from the eye color cheat menu.
the addition of the sliders....this was already amazing but you're improving in leaps and bounds! thank you so so much for your hard work!
Thank you too!
if I get a secret child from the royalty and legacy pack will it work for both parents or will the child only be geneticly related to the sim that gave birth to it?
It doesn't matter, a secret child has genetics of two parents anyway, so my mod doesn't change it
When looking for a video on how this mod works I ran into another similar mod and had a couple questions. They are able to reroll the genetics of an already created sim, is this something you are able to do yet or would consider adding? I also wanted to know if you thought their mod was ai, since you know coding or if it seems like they actually created it. Here is the mod. https://www.foxmademods.com/#top
Hi! First, did you find such video? I'm interested My mod allows to recreate a Sim with EA system, do you mean something else? And yes, that modder confirms AI usage, though, it seems, it's not vibecoded entirely. But I won't trust AI content anyway, plus I saw on Diacord Modding server a discussion about this mod, and it doesn't work as it should be.
hi, i'm jazz! i do translations, and i received a request to translate this mod, so i created a brazilian portuguese version. here is the link, in case you'd like to add it to the post so other brazilians can use it too: https://www.patreon.com/jezzamia/posts/traducao-pt-br-2-166389179
Hi, thanks! I'll add your link to the post
Hi absolutely love the idea of this, do you know if it interacts with Omegaverse at all?
Hi, thank you! I checked the code of this mod, and it seems to be working fine with mine
This looks incredible! Thank you! Small question about the sliders, it mentions that “unknown cc” sliders will be randomized on children. Does this mean all CC sliders will be randomized, or are there some CC sliders that will be correctly inherited?
Thank you too! They all are randomized by the game itself. I want to add a CC sliders additional map, but the problem is, that many of them don't have infant / toddler / child versions. So I'll need to make many tests before deciding which can be supported by my mod, and which can't
I'm very excited to download this today when it becomes public
It will be in public a couple of hours later, so I hope you love it 💗
when will it be available for download??
Today a bit later
I can't get the download as I don't have money for the membership :(
It will be in public today
This is sooo coool and needed !! 😭💜
Thank you! Btw, love your mods ;)
I'm so confused, I downloaded the mod but no .json file downloaded and I really don't understand how to change the settings. I'm quite new to mods, so I might be doing something really stupid. Can anyone help?
It will be generated once you launch the game. You can then edit the file I'll release the update soon so you'll be able to adjust settings right in the game
does this include dominant/recessive genes
No, because there is no such an algorithm in the game. Though, I'd like to make something like that in the future
in mccc i have this "Appearance_ParentAppearanceVariance": 10, should i also change it if it conflicts?
These settings don't conflict with each other. I set this setting too
why i cant downlaod file
not going to be public until the 7th august
This is so cool! Will it be possible to change the inheritance percentage from grandparents? For example, to increase it from 10 to a certain value?
Yup, you can set it as you wish
When will it be public?
On 7th August
Amazing! Can't wait for the public release!
Thanks!
How do I download this? I clicked the download button, but it's just taking me to a locked page.
It's in Early Access now. It will be in public on 7th August
I see someone else has finally dug around in the pregnancy and genetics code. How's the eldritch madness treating you?
haha actually I started modding right from the pregnancy and genetics code research, while working on my Twins mod though at this moment I think I know almost everything about this part of the game ;D
If my sim is pregnant now, will this apply? I have other sims who I want to have babies so it's okay if the changes won't affect it.
Yes, it will Genetics is applied at the moment of birth
This is amazing! Sorry if this is a stupid question, but how can we check if our CC has color tags so that we can decide whether or not we should select options using testingcheats?
Thank you! It's not mandatory, if you see incorrect hair / eye color, then use the cheat The color check happens only once anyway
Oh, this'll be really interesting when I dive back into live mode :)
Hope you love it :)
Oh my god, it is absolutely amazing from top to bottom. I really hope someone manages to put it into Spanish someday once it's ready; it’s going to be a huge improvement for the game. It used to be awful when a Sim would age up and suddenly look completely different, forcing you to edit them from scratch every year just to make them look right... and the same went for the Sims you don't control—it was terrible.
Thank you! Yeah, the current genetics system just doesn't make any sense