I think anything impressionable should leave a memory. And I think each memory should have a low to high effect. And that low to high effect should impact how a sim goes about their lives and it should take traits into consideration too. Like a gloomy sim that everyone is mean too, should have a harder time getting over it, or a good trait sim should have a harder time dealing with mean sims or a certain sim because it impacted their memory longer than say a sim who is cheerful all the time or who is mischevious themselves.
Of course some things that happen should be a high effect memory. One they always keep in mind and by that I mean when their fine or bored they may start to reminisce about it. Such as a wedding day and depending on the memory whether it’s good or bad effects their mood. And the memory remembers the emotion they felt then, so then it causes the sim to have the moodlet again while their reminiscing about it. A wedding day most likely would be a very happy time so it would temporarily make them very happy for how long? Well that would depend if it’s a low to high memory.
An alien abduction would be traumatic most likely, and make a sim fearful of aliens the rest of their life, when they begin to reminisce it would cause very tense moodlet or very fearful moodlet.
A ghost may cause this too, and if the memory is bad enough maybe it even has a wild chance of causing so much stress to the sim it causes death. A sims first kiss should be a high bar memory we’re it’s logged and they through out their life reminisce over it or think about that particular sim they kissed.
