Well, let's start with what the gender preference is: In The Sims 4 the gender preference is like a hidden score checker and can be seen if you have MCCC. It has a score that goes from 0 to 100 for male and female, and this should supposedly set your sims preference through actions, such as you commanding them to flirt with someone. If you make your sim only flirt with male sims, then the score will be set to male: 100. Female:0. Or you make them flirt with both male and female, then they get 100 on both, or some other number, depending how much and equally you do it. The high score means that is your sim's preference.
It is not set in stone. It will change depending on what you make them do romantic interactions to.
A system that should supposedly work, but it doesn't. For one, compared to the previous gender preference system from TS3, it doesn't have a negative score, just 0. The negative one made your sim not being interested in that sex at all. In other words making them straight or gay. The 0 score makes that impossible.
It also seem to be strange in what interactions it thinks add to these scores. Sometimes friendly ones adds to it aswell.
Nor does it seem to follow its own scores that well since sims rarely seem to actually have a preference even if one is at 100 and the other is at 0. Sims just flirt with everything when they are in the mood to flirt.
In the end, the system isn't good. Not only is the hidden nature of it confusing and leaves more questions than answers, but it doesn't seem to work either!
I think it would be better if they just gave us a CAS option to set sims preferences. Perhaps on a slider, where one end is 100% for the opposite sex, the other 100% for the same sex and in between those all the combinations for both sexes. Also, an asexual option below it. Or maybe a slider on that one aswell. Newborn sims would of course have these set randomly.
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Now, after that rambling I may call an attempt of explanation. The Patch note!
I think the patch note means, that sims will no longer autonomously flirt with sims that have a very low score.
But that's purely a speculation from me.
