This is a set of eight very simple traits to track your legacy families. They are inherited from parent to child and all it does it give them a trait called so that you will know which sims your sim is related to after you've lost track, or just to have it there. There is no added effect from being near family--your sims can have a close or difficult relationship without this trait affecting your story.

The traits included are:

Family Member
Clan Member
Kinfolk
Descendants
The Lineage
The Dynasty
The Legacy

If you want to customize the trait names that are available in your game, I made a tutorial here.

Reginald's Family Portrait

Reginald's Family Tree

For your founder (or any sim you're applying it to manually), you can find the Family Member reward traits in the reward store for 100 Satisfaction Points, or you can cheat it on to them (for example, by using MCCC > MC CAS, or you can turn on testing cheats and use a cheat like 'traits.equip_trait amethyst_lilac:family_member_reward_trait_basic').

How to search for the trait using MCCC

Then, when they have biological children, they will inherit the trait. From Owen down to baby Tabitha.

Owen's 8-generation Family Tree

Owen's traits, including Family Member, starting with Owen and ending with Tabitha

A picture of Owen's family

Tabitha's traits, including Family Member

If you use Show/Search Sim Info (updated by Frankk), you can search all sims in the world to find your family.

The traits are Base Game Compatible. They are not valid for reincarnation.

There are now custom strings. They are currently all in English except for the original Family Member--I went through and copied the name for that from the game's string, so that one string should be in your game's language.

To have the trait appear in the reward store, be inheritable, or show up in thee filters for clubs/small business customers/getaways/custom venues, you NEED Lot51's Core Library. Otherwise you will need to cheat the trait on, and it will be cosmetic only (no inheritance). But if you want to use it for that, feel free.

They are not mutually exclusive--if you have two sims with different family member traits have a baby, the child should have both traits.

It DOES apply to science babies.

It does NOT apply to pre-existing children, children made in CAS, adopted children, or relationships created in any other way then birth or science baby, but you can manually add the traits to them in live mode.

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The only cc used in the screenshots is Kijiko's eyelashes (various versions) and Lin Natural Nails

Poses (first pic only) are a mix of [ROSELIPA] I GOT LOVE, Seated Poses 3 - Pose Pack by StarrySimsie, and Family Portrait Collection: I by onyxsims

Thanks to:

The RivRel mod (long broken and abandoned now) for giving me the original idea, even though it wasn't quite what I wanted.
Lot51's TDesc Builder and to Sims 4 Studio, which I used to make the trait.
Waffle on discord for helping me get the last piece I couldn't figure out on my own.

Updates:

March 15, 2024: Thanks to recent changes to Lot51's Core Library, the requirement for Mal22's Trait Tracker Injector has been removed. Now requires Lot51's Core Library only.
Nov 10, 2024: This was updated to match current game tuning. While not updating today won't break your game, there were an alarming number of changes to the SimData, so who knows what the next patch will bring? PLEASE update.
May 29, 2025: Added extra trait options, and made a tutorial for how to customize them for your save (so you can have a Smith Family trait, for example). This was actually done a while ago, but just uploaded here today.

Family Member Trait