Sims disappear from family trees and relationships are missing

[9419f0ed060180db]

Product: The Sims 4
Platform:Mac
Which language are you playing the game in? Deutsch
How often does the bug occur? Often (50% - 99%)
What is your current game version number? 1.95.207.1230
What expansions, game packs, and stuff packs do you have installed? University Exp.pack & parenthood game pack
Steps: How can we find the bug ourselves? In Family trees and relationship panels
What happens when the bug occurs? 1. Sims randomly disappear from family trees, mostly when I reach the third generation (e.g. Bella Grusel is gone from the family tree, only an anonymous panel is left, Mortimer is still there) and sometimes even in gen 2, in this case sibling-relations where one of them died seem to be affected most (e.g. a sim with two brothers suddenly had only one left in the family tree, because the other completely disappeared when he died, although the parents who are also dead are still showing up). 2. Relationships disappear completely, some sims only know the others in their household although they originally knew their siblings they grew up with, romantic partners, best friends etc. One sims even forgot her babies father. This happens mostly to families I play every other week, less to those I play every other day.
What do you expect to see? Functioning and ideally restored family trees and relationships.
Have you installed any customization with the game, e.g. Custom Content or Mods? Not now. I've removed them.
Did this issue appear after a specific patch or change you made to your system? Neutral/Not Sure 

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Not my screenshot but it looks exactly like that

[Elsa92]

I am also playing Sims 4 on a Macbook, and I have the same problem. I have just been playing with my first family, but relationships in the neighborhood, from work and school disappear all the time. When my sims meet someone, a while later they don't know the person anymore. Even when I introduce them to my housekeeper, a few times later they have to introduce themselves again.. very annoying. Also when I want to invite people for a party or an event, the sims I want to invite are not between the sims I can invite. This was never the case in sims 3. 

[Xila31]

This is not a bug. It's happening because the game removes ghosts from the game and is called culling. Once a ghost is removed, it deletes the Sim entirely as if they never existed. Gen 3 is around the time when this happens a lot and become noticeable,  it includes Sims that are in your family. You can prevent the culling of specific ghosts by strengthening the Sim's connection to the world at their grave or urn. If you don't have their grave and don't use mods to make them a new one and summon them to it, then they will be lost forever. Once the Sim disappears, the connection to the family tree is lost as well, because that relationship no longer exists.

Culling is important to the health of the game because the more Sims and ghosts that exists, the more memory is needed for the game to run and it increases lag and other problems. However, it is unfortunate that the family tree is incapable of archiving Sims and relationships and they just permanently erase. It was my hope they were going to fix this with Growing Together but they did not.

The game will also cull non-ghosts from time to time but it's mostly ghosts.