If a Sim gets cosmetic surgery using adeepindigo's Cosmetic Enhancements mod and then has a child, that child inherits the surgically altered look, not the parent's natural one. I love that mod, but that detail has always bothered me.

Cosmetic Genetics fixes that, ensuring children inherit their parents' original features without touching the parent's current appearance at all!

Requirements

Cosmetic Enhancements by adeepindigo
Base game.
Script mods enabled.
This is optional but I highly recommend these Plastic surgery scars by scandisim for adding a pinch of realism

How it works

The first time a Sim completes a Consultation (the Cosmetic Enhancements interaction that precedes surgery), this mod quietly stores a snapshot of their appearance. The mod will store it in a file called cosmeticgenetics_snapshots.json in your Documents\Electronic Arts\The Sims 4 folder. If you want this mod to work, do not delete that. Whenever that Sim becomes a genetic parent afterward, the mod temporarily substitutes the stored "before" appearance into the blend, then immediately restores the Sim's real, current, surgically-altered appearance right after. There's no flicker and no visible change to the parent. Net effect: the parent keeps their surgery results exactly as before. Their kids inherit looks based on the parent's "genes", not their current appearance. Only the snapshot from a Sim's first Consultation is ever kept. Later surgeries don't update or overwrite it. Multiple sims in the same save (or across multiple saves) can undergo multiple surgeries and the mod shound't break.

Installation

The usual drill for a script mod: just drop the [SpcyYogrt]CosmeticGenetics.ts4script file in your Documents\Electronic Arts\The Sims 4\Mods folder.
One folder level deep is fine (e.g. Mods\Cosmetic Enhancements) Any deeper than that might make the mod not work.
Don't forget to install Cosmetic Enhancements by adeepindigo and all the other requirements described in that mod's page.

Limitations and Compatibility

If a Sim already had surgery before you installed this mod, their pre-surgery look was never captured and can't be recovered. The fix only applies going forward from each Sim's first Consultation after install.
If you heavily edit one of these Sims in CAS before their first Consultation, that edited look is what gets snapshotted.
Should be compatible with anything that doesn't itself patch `apply_genetics` on a Sim's base appearance data. Please use caution with other heavy pregnancy, offspring, or MCCC genetics settings, as they might conflict.
To be safe before starting a long storyline, run a quick test: Create two identical Sims, give at least one of them a drastic plastic surgery, have them have a baby, and check if the baby inherits the parent's original look.

Disclaimers

Built to complement Cosmetic Enhancements by adeepindigo. Not affiliated with or endorsed by that mod's creator. Does not use any code from the original mod, only adds to it. Also does not edit the code from the original mod.

The code for this mod was mostly generated by AI tools. I am not a programmer, my contribution to this project was designing the core logic for the mechanics, managing the development steps, and thoroughly testing the mod. While I don't take credit for the code, if you encounter any issues, please leave a comment and I will help you as best as I can! If you are an experienced programmer interested in taking this concept under your wing, please hit me up!

If this project ever generates any revenue, 90% of the proceeds will be donated to local animal shelters and other non-profit organizations.

Add on for Cosmetic Enhacements by Adeepindigo - Realistic Genetics