Genetics Overhaul Collection: No Weird Age Up and Random Genetics Gets an Incredible Makeover for Better Looking Sims

Genetics Overhaul Collection: No Weird Age Up and Random Genetics improves CAS genetics, fixes odd age-ups, and creates more natural-looking Sims.

If you’ve ever watched a perfectly normal child grow into a teenager with a tiny chin, oddly placed eyes, or completely different facial proportions, you’re definitely not alone. Genetics Overhaul Collection: No Weird Age Up and Random Genetics by SonozakiSisters is here to tackle one of The Sims 4’s longest-standing genetics frustrations with a complete overhaul of how the game handles randomized facial features.

This ambitious new collection doesn’t simply tweak a few sliders. Instead, it rebuilds the game’s genetics templates to create much more natural-looking Sims throughout every generation while keeping randomization feeling fresh.

Genetics Overhaul Collection: No Weird Age Up and Random Genetics Reworks the Entire Genetics System

According to SonozakiSisters, this has been one of their most requested and technically challenging projects to date. The mod completely remakes the CAS genetics templates that The Sims 4 uses whenever Sims are randomly generated.

These same templates are also responsible for how Sims change as they age, meaning the improvements affect both newly generated NPCs and existing Sims growing from one life stage to another. Instead of allowing facial sliders to swing wildly, the mod applies much stricter randomization limits that help preserve more balanced facial proportions over time.

One of The Sims 4’s Biggest Genetics Problems Finally Gets Fixed

One of the standout improvements targets the infamous “small chin” problem that many longtime players have noticed over the years.

SonozakiSisters discovered that The Sims 4’s genetics system tends to favor lower chin slider values rather than increasing them naturally. As a result, generations of Sims often end up developing unusually small chins, even if their parents or grandparents had perfectly average facial structures. This collection corrects that behavior so future generations are much less likely to inherit those exaggerated features.

More Natural Faces Without Removing Variety

The overhaul doesn’t stop with chin sliders. The creator also adjusted the minimum and maximum limits for several important facial features to keep random Sims looking much more believable.

The new genetics system places improved limits on eye size, lip size, nostril size, eye position, nose position, mouth placement, eyebrow angles, shoulder length, and several additional CAS sliders. The result is a much healthier range of facial variation without producing the extreme combinations that can sometimes make randomly generated Sims look unusual.

NPCs Still Have Personality, But Fewer Strange Faces

SonozakiSisters points out that not every unusual-looking NPC comes from genetics alone. Many odd appearances actually come from the facial presets that The Sims 4 randomly selects.

For players who want even better results, the creator recommends pairing this collection with Presets Selection for Randomized Sims by SimplyAnjuta. That companion mod removes many of the less desirable facial presets from NPC generation, helping random townies appear even more natural alongside the new genetics system.

Compatibility and Requirements

One of the nicest parts of this release is how easy it is to install.

The mod is completely Base Game compatible and does not require any additional mods or dependencies. It also does not conflict with MC Command Center (MCCC), making it easy to add to existing saves.

The only known conflicts are mods that edit the game’s Client_CASModifierTuning files, since those affect the same genetics templates used by this collection.

Final Thoughts

For players who care about family gameplay, legacy saves, or simply want better-looking randomly generated Sims, this may become one of those essential quality-of-life mods that quietly improves every save file. Watching children grow up without completely unexpected facial changes makes long-term gameplay feel much more satisfying.

If you’re interested in giving your Sims a more natural genetics system, be sure to check out SonozakiSisters’ full release page for additional information, compatibility updates, and future improvements.

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