I've made up a few new Sims for my neighborhood since installing Legacy, and Chemistry seems to be completely broken for them. I understand pretty well how it works in the game, and had designed Sims to have good chemistry with existing Sims from before the Legacy install. And... nothing. For example:

Sim a was designed 15 years ago, and has mutual 3-bolt Attraction with another Sim who was born then. After I installed Legacy, I decided to give her a sister, who is identical in all respects (genetically, turn-ons, Aspiration, etc) with her sister. In fact, she's a clone, with only a few cosmetic differences. She has *zero* attraction to her sister's boyfriend, and he has *zero* with her.

I've also made some Sims who were meant to be attracted to certain others in the 'Hood who are without suitable soulmates. Again, they were set up intentionally to be the perfect match for certain other Sims, whom they have met, and are completely underwhelmed. There is no attraction on either side for any of them. This applies to six new Sims I have made since installing Legacy, and seems to me a good indication that something is broken or changed in the Chemistry algorithm.

It doesn't really matter, since I pretty much ignore chemistry in favor of whatever story I'm telling with given Sims, but it's annoying that Sims who were *designed* to be perfect for each other couldn't be more bored if they wanted to. At least there's no negative chemistry between them. I also seem to be getting more negative reactions in conversations than I used to, from Sims whose interests should be perfect matches, but that's harder to quantify.

Anyway, I was wondering if any other Legacy players had experienced this oddity, or if it is a quirk of my game only. One possibility is that I have the InSiminator's relationship balloon on my lots, to turn off jealousy (since the mod I had that did that appears to be gone; all that I can find is one that turns off jealousy for Sims without relationships, which is inadequate for some of the group marriages in my neighborhood). But if that were conflicting, one would think it would affect all Sims, not just the ones made since Legacy. Existing Chemistry is still working fine, it's only the new Sims who are bereft of it.

Addendum: I just ran the experiment again with a couple of clones from before-Legacy. They hadn't yet met each other's spouses, who had full chemistry with their mates. As soon as they met the clone, they exhibited full chemistry, as they should. So that would seem to confirm that new Sims are broken in that respect. What a weird thing.

-- Mal

Brand new sims that you create don't have any gender preference, so they don't have chemistry with anyone. If you want them to have chemistry with people, you have to set their gender preference.

I've never done that in my life. I don't even know how to do that. When did that start?

-- Mal

Obviously you have, or none of your sims would have any chemistry. Either you can use a mod, or just do it the intended way of having them interact romantically with whatever genders you want them to be attracted to.

Actually, it's not necessary. The clone I was just talking about did a "Check Sim Out" flirt action, and immediately gained 3 lightning bolts of attraction.

Still weird, because Sims used to be attracted without flirting at all, but I'll take it this way. Just have to get their relationships high enough so they won't be shot down when they flirt.

But really, I have no memory of ever setting a Sim's attraction in the game. I will note, for what it is worth, that I have Free Will disabled on every lot in my 'Hood, just to avoid random flirtations and unintended romantic interactions.

-- Mal

Like I said, doing a romantic interaction like check sim out will set the gender preference, I don't know why you claim to not have a memory of doing it while also describing how you did it. And yes, it is necessary, if you don't do that, they won't have chemistry with anyone. The game has never automatically assigned a gender preference to newly created sims. There are a very small number of premades that have preset gender preferences, but CAS sims start without one.

I think it's easy enough to just play without noticing that you're setting your sims' gender preference. Sometimes you do interactions that are on the romance tree or whatever you'd call it, without realizing that they are, and sometimes your sims flirt autonomously.

Ha, my Sims never do anything autonomously. They are slaves to my inexorable will.
Well, except for community lots. Never know what they'll get up to there.

-- Mal