One major complaint of The Sims 4, primarily, is that some players who have played previous entries find it to be too easy, predictable, etc. Sims are harder to kill, harder to neglect, and tend to have a happier disposition depending on traits and other factors. It doesn’t feel like there is enough drama or consequences, even in some systems added with expansion packs that are intended to do so, like Royalty & Legacy’s Scandal System, or Life & Deaths Bucket List/Unfinished Business system. Also, you can control so many factors of their lives, that it feels closer to the idea of a dollhouse simulator than a life simulator for many players.

A well-known feature of The Sims 3, the first mainline The Sims series entry to feature a personality traits system, was that how happy your sim was upon aging up would influence your choices as a player. Sims who were raised well and happy in their life stage would get positive traits, or you would have full control to pick their next trait. If a sim grew up unhappy, neglected, or just negatively in general, they would randomly inherit a “negative” trait. These would include traits like “Evil”, “Slob”, “Grumpy”, etc.

With The Sims 4, the other mainline entry that has a personality traits system, you can always choose a Sim’s traits upon aging up. You can opt to randomize them, as well, but you are still largely in control. The only negative to sims growing up unhappy, neglected, or unfulfilled is a random age-related trait (Like Unhappy Infant), or missing out on possible bonus traits that could influence their life later. It feels less like a punishment, and more like a slap on the wrist for being downright neglectful.

A Sims 4 Aging Mod With Sims 3 Aging Up Mechanics?

Bestie tyjokr has made a mod bringing a mechanic that takes after The Sims 3's age up system, where poor upbringing can result in you not being allowed to pick traits yourself! Can make for some interesting gameplay! pic.twitter.com/KDX1K2Tqo8

— Lunar 🇵🇸 (@lunar_britney) May 3, 2026

Community member and modder Lunar_Britney posted on X recently, sharing a new mod currently in early access that may be the answer to the complaints of these exact players!

Modder tyjokr, someone who always enjoyed the variety that came from this Sims 3 feature, decided that it doesn’t have to be this way. Now in Beta testing, the “TS3 Age Up” mod by tyjokr will now take into account your sims experiences to indicate whether you get to pick a trait or not.

The System Itself

To start off, there was a change in the mod during beta testing where infant traits are now entirely random. This means that when you decide to age up a newborn from their bassinet to infancy, what trait they receive is uncontrollable, as there isn’t much to do outside of basic care for newborns and they do not inherit traits based on this experience.

It varies by age stage and effects every age differently, because of the way the aging system works. Only two ages have reward traits related to their upbringing, which are Infant and Toddler. Infants can receive Unhappy Infant, Happy Infant, and Top-Notch Infant based on their needs, milestones, relationships, and mood at time of aging up.

Infants who age to toddlerhood with low caregiver relationships, low needs, or tons of bad buffs will have the Unhappy Infant trait. On the other hand, toddlers aging into children can receive the Top-Notch Toddler trait or the Happy Toddler trait based on their skill levels. Since toddler skills range from 3 to 5 levels, Happy Toddler is given with all skills at 3 or higher, and Top-Notch Toddler is given with all skills maxed out.

After these stages, the most vital aspect of whether or not you will get to choose a trait, or what traits your sim can get, is their grades. Per tyjokr’s Patreon mod page…

In-Game

Infancy to Toddlerhood

To test this mod out, I created a couple and cheated two pregnancies for a total of four newborns. Throughout their growing up, I adjusted their needs, skills, milestones, grades, and more to account for all the possible outcomes at each age stage.

Growing into infancy, the traits were all randomized, but somehow three out of four of the babies were Wiggly, with a single one being Calm. After that, milestones, care, and needs were a huge part of how they grew up. This meant that each child needed to grow up entirely differently to be able to show the full range of the mod itself.

To test this mod, my sims were truly terrible parents. They did not care for nor love their children equally, they neglected certain kids, etc. Just downright awful. Because of this, each infant had a different experience going into toddlerhood.

Suzanne was doted upon. Her parents had her in their arms all the time, played with her, kept her needs topped up, and had insanely high relationships and attachments to her. Upon aging up, she had multiple happy moodlets about the affection they give, milestones she achieved, and her needs being fully. Since she received the Top-Notch Infant trait, I was able to pick her trait upon aging up. I ended up randomly rolling the Independent trait.

Bethany, her sister, also received adequate care, but not as much as Suzanne did. She was happy, cared for, and hit some milestones, but she did not have tons of attention nor did she receive all the doting upon that her sister did. Upon aging into toddlerhood, she inherited the Happy Infant trait, and therefore, she rolled a “positive” random trait that I could not choose. She was a Silly Toddler.

Lastly, Jolene and Jayden were kind of just.. ignored. They didn’t get taken away, but their needs were not great upon aging up, their milestones varied between being completed or completely disregarded, and they had highly neutral or even low positive relationships with their parents. Due to this, Jolene grew up with the Wild trait, and Jayden rolled the Clingy trait, which are two of the more “negative” toddler traits.

Toddlerhood to Childhood

Since the outcome of a Sims toddler years is determined based on their skill levels upon aging up, it depended on the teaching, experiences, and overall learning your toddler received. Age them up too soon with not much experience? You don’t get to pick the trait and there is a chance of any trait available to children being rolled.

More significantly? This is where your sim begins to develop the traits that they will have for the rest of their lives. Since infancy and toddlerhood have their own traits, it is almost not as much of an issue as it is in the later years, where the result of their toddler experience will possibly change their entire personality and dictate it for in-game years to come.

Once again, Suzanne had the textbook perfect experience. Her needs were kept up with, and she was taught everything. With maxed out skills and being happy and healthy, her trait could be picked and there were no random consequences. Suzanne gained the Cheerful trait. However, Bethany also had a good experience this time around. Bethany gained the Perfectionist trait.

Jolene and Jayden, again, were forgotten. Jayden was able to get skills to three, which earned him the Happy Toddler trait. His randomized trait upon aging to a child was Recycle Disciple, which I wouldn’t say is really negative or positive. However, Jolene didn’t really level any skills. Since she did not receive a reward trait, all skills were possible, and she rolled the Evil trait.

Childhood to Teen

Grades are everything for this mod now, with Children and Teenagers being much more independent than the younger life stages. While aspirations also seem to be a big part, those already give reward and bonus traits upon completion. Your ability to pick traits once a sim ages to a teen is based on how good of a student they were, and how much you or your sims fostered their education.

This time around, Bethany was able to do the best in school. She was an A student, had all her marks, and performed incredibly well. This meant I was able to choose her trait, and she rolled the Bookworm trait upon aging to a teen.

Suzanne and Jolene were middle of the road. With them being B and C students respectively, they weren’t shining stars, but they weren’t flunking out of class either. Their traits were random, but not inherently terrible. Suzanne being a B student meant that she got a random trait but negative traits were excluded, meaning she gained the Horse Lover trait. Jolene being a C student meant that she got a random trait as well, but all traits were up for grabs, and she rolled the Overachiever trait.

The poor, poor, Recycle Disciple Jayden did not in fact do well in school, ending his childhood as a D student. D and F grades are treated the same with this mod, so either way, it wasn’t a great outcome. Upon aging to a teen, he rolled the Gloomy trait.

Teen to Young Adulthood

Once again, the importance of grades is vital if you want to be able to pick your sims traits. The range and grading in the mod are the same. To recap, A Students will have a pickable trait, B Students will have a random positive trait, C Students can roll any random trait, and D or F Students will have a random negative trait.

Bethany hit her marks and ended high school with an A grade, giving me the ability to pick her trait. Her final trait was the Idealist trait. Suzanne was a B student, and rolled the trait Green Fiend. Jolene was a C student, and rolled the Mystical trait. Lastly, Jayden ended high school with an F grade, and he rolled the Evil trait as a result.

The End Results

I tested this mod in a new save to get a clean slate and see how it goes, and I know I am keeping it in at this point. I am family and legacy-style player, and I am someone who deeply enjoys my game when everything is not entirely under my control. Having Sims who grow and develop as they age without me guiding every single thing is so much fun, and it gives them more personality and more permanency when I play, as I adjust their lives to accommodate new and unexpected traits.

The four children that grew up are interesting and varied, and once they were young adults, I got a very clear idea for how to style them based on those traits that I might not have picked if I had a choice in the matter. Even as someone who randomizes traits generally upon aging up in my normal gameplay, I cannot say I haven’t hit the randomize button a few times because I didn’t really like the trait it gave me. Having no choice, somehow, made it way more fun!

This mod is currently in an Early Access/Beta Testing Period, and will be released to the public soon. Although a specific date is not yet listed, modder Tyjokr did note in the comments that it will likely be released this coming weekend as there were no prominent issues, and it gives them time to account for custom traits players requested.

Do you like mods that give more of a challenge, or take away some of the in-game options? Is there something from past games you would love to see brought to Sims 4, either officially or through mods? Comment below and let us know!

Keep an eye out for more mod guides, overviews, and deep dives from us at The Sims Community!