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Genetics and Visual Features Inheritance in Paralives
🕑 Added 2025-08-08 14:05:04 +0000 UTCHappy Friday, Anna here!
Today I am going to talk about the genetics system in Paralives, something we started working on a long time ago (back in 2020… time goes by so fast!). I’ve been revisiting the whole system recently to make it work with all the updates to the Paramaker that have been implemented since, and to integrate it into the pregnancy gameplay. A perfect opportunity to show you how it holds up in action!
Note that this post is for Patrons only; please don’t share it. Thank you! 🔒
🧬 Different Types of Inherited Traits
In real life, our physical appearance is influenced by the genes we get from our parents and lots of environmental factors. Don’t worry if you don’t remember your biology class about dominant and recessive genes, there won’t be a test!
Our main challenge in Paralives was to create a system that lets the player recognize certain traits passed down through their generations of Paras somewhat realistically, without diving into overly complex genetic rules. We wanted things to feel believable, with some fun details (for those of you who do remember Punnett squares 👀) while keeping the system lightweight and consistent with character customization.
We use different inheritance rules depending on the type of trait, and we’re focusing solely on visual aspects here. Let’s go through them!
1. Facial Features: Straight From One of the Parents
Our goals with facial features inheritance are quite simple and definitely not nearly as complex as real-world genetics. We essentially want the player to be able to recognize that “They have their mother’s nose!” or “They have their dad’s jawline!”.
How it works:
For each facial feature (like the nose, chin, etc.), the child inherits all the relevant sliders from one parent, chosen randomly. For example, they might inherit their entire set of nose sliders from their mom, and the cheeks from their dad. This helps keep things coherent and avoids weird mixes of incompatible sliders, which can quickly lead to ugly or extreme results.
Here is our favourite couple from the trailer video and the two children we created from them with the genetics tools of the Paramaker. Aren’t they cute?
2. Height: Partly From The Parents, Mostly Up to Chance
As you know, changing the height of the characters is central to Paralives, and we’ve been trying to make this happen since the very beginning of the development. Having this possibility of different heights adds a lot of uniqueness to characters and makes the world feel more diverse and alive. Our goal for the genetics part of height is not only to get this idea of height being inherited, but also to add some variation to it so that children of the same parents don’t necessarily have the same height. We want the player to say things like “This family has giant genes running in it!” or “This child grew to be taller than both their parents!”. Waiting for kids to grow before knowing which one is going to be the tallest of the family is a nice little detail that this system makes possible!
How it works:
We split heights into three categories: short, medium, and tall, with different ranges depending on the Para’s sex (resembling real-life statistics). When generating a child’s height, we randomly pick one parent’s category and apply it to the child. Then we randomize the exact value within that range. That means your Para might be “tall like his mom”, even if they’re not exactly the same height.
The big brother is already taller than everyone!
Note: In the Paramaker, you can make a genetic child from two same-sex parents, but during gameplay, the parental couple will always consist of one para that can get pregnant and one para that can get others pregnant (you can edit these per character in the Paramaker).
3. Eye Color, Skin Color, Hair Color and Texture, Freckles: Your Textbook Dominant and Recessive Genes
For those traits, instead of getting the direct value from one of the parents, we wanted to build a more complex genetics system that reflects simplified dominant/recessive models that are already documented in real life. These are the only traits that are able to “skip a generation”!
How it works:
We built a simple system of genes and alleles to simulate how these features are passed down. Some traits are dominant, meaning they only need one copy of the gene (allele) to appear (like brown eyes). Others are recessive, which means they need two matching alleles to show up (like blue eyes). I already talked a little about the two-gene model for eye color in this very old post, but here is another example that we implemented for hair texture.
There’s one gene for hair texture, and it can have four possible alleles: straight, wavy, curly, or coily; with coily being the most dominant, and straight the most recessive. In other words, the more curls you have, the more likely the trait is to "win" when mixed. Let’s say a Para gets one curly allele from their mom and one wavy allele from their dad. Since curly is more dominant than wavy, the Para will have one of our curly hairstyles, chosen at random. But the wavy gene is still there, and it could show up again in their child, if paired with another recessive allele!
In this example, the mother’s hair is coily and the father’s hair is straight. In genetics terms, the dad has to have (Straight/Straight) alleles, since straight hair is never dominant. Since the kid has curly hair, it means his mom has (Coily/Curly) alleles and he has (Curly/Straight) alleles. 🤓☝️ One curly grandpa or grandma would have been very proud!
👩💻 Application of the Genetics System
We use the genetics system in several different situations:
When creating a Para from scratch in the Paramaker: The game analyzes their current features and deduces the genome data corresponding to the actual look of the character. If the character has “unnatural” traits (like pink eyes or green skin), their genetic data is randomly assigned.
When creating a Para from two parents: Whether you’re in the Paramaker or Live mode gameplay (by getting pregnant), the game generates a child by following the inheritance rules we’ve explained above, from the genetics data of the two parents.
When adding a parent or sibling in the Paramaker: The system uses existing genetic data to generate the new family member so that everything fits together nicely.
Not implemented yet (but might be an update in the future): An advanced genetics interface for all the geeky players out there wanting to control their Para’s genetics themselves.
🍼 Note: Babies and toddlers don’t have access to full sliders, so their features might look a bit generic at first. But don’t worry, their genetic data is still computed and saved, and once they grow up, they should reveal their true heritage!
Here is the updated look of the interface for creating characters with genetics! Note that right now, only two options are available (Create Child, Create Twin), but there should be more soon (Create Parent, Create Sibling). You can choose the sex and the life stage of the child you want to randomize.
🛠️ Hacking Your Para’s DNA With the Mod System
As with most of our in-game systems, genetics are widely moddable. You can add, remove, or modify any trait category that supports genetic inheritance, set up the sliders you want inherited (or not), and more.
Some examples of applications could be:
Create a new alien species with green and grey skin tones (with green as the dominant color)
Make “unnatural” colors (like bright pink eyes or blue skin) inheritable
Add new accessories, like devil horns or Shrek ears, and make them inheritable too (pretty sure Shrek ears would be a dominant trait, in my scientific opinion)
Do you have any other ideas for genetic traits that you would like to mod in Paralives? 👀 I’d be happy to hear them!
There are many little details we are still working on to make the most believable and good-looking children Paras, but I hope you enjoyed this little tour of the genetics system to date!
That’s it for me!
Have a wonderful weekend,
Anna
Comments
AmbiguouslyAnonymous
The only genetics-related thing I'm hoping for that's not mentioned at all in this post is hand-dominance. Whether a child para is left or right handed being random but heavily influenced by parents' handedness
AmbiguouslyAnonymous
I appreciate that things like the skin colour for interracial couples isn't only the midway point between the two parents. It seems like biracial paras are actually able to inherit very dark or pasty white skin too? Really cool if so! One thing I do hope the system is able to do is to look at things like: 1. at least one parent has blonde gene + 2. at least one parent has redhead gene = child para has chance to have Strawberry Blonde hair, even though neither of the parents had that specific hair colour. I also REALLY appreciate you mentioning modding at the end. So we'll be able to EASILY mod in inheritable rainbow anime hair colours AND make new inheritable species/lifestate/fantasy race traits like ears and tails. Really really awesome!
ChosenSquirrel
With Nraas (Sims 3) you could control how much of an effect Grandparents and parents held on the appearance of children. Would be cool if people could mod that in here. So a huge nose has a change to skip a generation. But as it is this makes a lot of sense and should be soild
Leaf
Ask controversial as the sims for genetics system has been,for me one of the things I had liked about it was that it did not strictly only follow the parents geans, it was a gamble of how much they looked like their parents which felt slightly realistic to me as in real life people can inherent genetic traits from all there past relatives and it gave more personality to each individual child
Dll :3
Por favor, por favor, por favor nos possibilite adicionar caudas felpudas e orelhas aos Parafolks pra criar um Para demi-humano, tipo Raphtalia!! 🥺😬😶🌫️
Kat Mac
It's not clear from the post, but I hope you can get a mix of parents skin, hair and maybe eye color. My dad has black hair and brown eyes and my mom blonde hair and blue eyes and my siblings and I all have brown hair (of varying shades) and hazel green eyes. All of our skin is in between too. I would also love to see a brunette para and a redheaded para have a kid with auburn hair, or blonde/red for strawberry blonde!
Shavonte
I don't know if this will be included but making the skin details (i.e. vitiligo, freckles, birthmarks) inheritable is a must. So many games leave this out and it breaks up the gameplay. If it is not automatically included, hopefully with the mod tool we will be able to. add it.
LightDeficient
I have no words other than LOVE IT
Rose Blanchard
I think it means it will be heritable but the dominance is random. If you click on the link for their old genetics post, it says you can unlink traits. For instance, if the character has pink hair, it can be treated as dyed hair and not a genetic hair colour if you unlink it. I'm not sure if this is just for hair, or if it's for all features.
frenchifries
This all sounds super cool and exciting! I did want to clarify something though. It says "If the character has “unnatural” traits (like pink eyes or green skin), their genetic data is randomly assigned." Does this mean, for example, if I create a Para with purple skin and pink hair, the game will randomly decide if these traits should be considered dominant or recessive, but that they could still pass them onto their offspring? Or does this mean that they will receive randomly assigned "real" genetics that differ from their displayed traits, like their skin genome will be considered "dark" and their hair genome will be considered "blonde" for example? Meaning their offspring can't inherit their "unnatural" traits? I would hope when we eventually get the option to edit their genetics ourselves we can decide whether or not we want these "unnatural" traits to be heritable. I like playing with fantasy creature characters so it would be nice if I could have a whole family of pink and purple babies.
Hollie Burton
This is SO sick. I can't wait!!!
Dallinlory
I'd like to note that in real life people actually can have pink, red, and purple eyes, and that such are genetically inheritable. These eye colors are displayed in people with albinism. Though I recognize that y'all probably have a lot of work on your hands right now, and this is hardly a top priority, it could be nice to add a natural eye color system for these traits.
Another Plumbob
I love that you’re putting attention where it’s needed and being efficient with resources where it makes the most sense too. It’s so clear you’re players and this game is a product of love and it really shows with every system you showcase
Leah Beth
I just have this euphoria feeling of how incredible it felt to create a sim for the first time but this will be that x a million. To me the height implementation is really amazing. I just really can’t wait
I kinda forGoT
This sounds so cool!
Yassou 야
Ce système de génétique est intelligent, efficace et tout simplement magnifique !! Bravo à toute l'équipe c'est du beau travail !! Je suis impressionnée par la ressemblance des enfants avec leurs parents, c'est une superbe idée de mixer les traits de cette manière et le fonctionnement des tailles, de la texture des cheveux, tout est super bien pensé ! C'est un réel plaisir de voir ce que des personnes alliant intelligence et créativité réussissent à créer ♥ BRAVO
Danielle Ross
I am completely in awe. HOW COOL IS THIS?! I have been absolutely blown away by the development of this game and I am so so so excited to play.
Emma Schroeder
this is something I was curious about, and I'm super happy to hear about the process!! I absolutely love genetics and knowing that you guys put this much effort into it makes me really happy
Josephin01
As I understand the concept of gender in Paralives, the characters don't have a real gender. You can choose whether they have breasts, whether they can get pregnant or impregnate others, etc. In that sense, it's a human being who has no gender at all, and we have to breathe life into it and give it a personality. So, wouldn't this mean exactly what you wrote/what you want, or have I misunderstood it?
Nymmkins
Do you have a plan to allow players to create gender non-conforming, trans, and intersex people?
Morgan McGlothan
I’m curious about recessive genes - you mentioned that if one parent has brown eyes & the other blue, their kids will have the dominant gene (brown eyes). Is there ever a small chance for the recessive gene to pop up in one of the immediate children? Or would that only potentially happen in the next generation?
Nocher Chubuk
Honestly, I just hope it’s there at all, because in «you-know-what 4» it’s basically non-existent — only body shape and the exact picked coat color get passed down, no mixing from parents, and anything you painted yourself doesn’t carry over either.
AureRed
Can't wait to see how animal genetic system will look because there is big communities for Horse genetics and games about it ;)
pekeniax
This is just awesome! I love how genetics work in the game and can't wait to be amazed when my future parafolks show their granma/grandpa recessive features 💚
Morgan
I am sooooo excited for this!
