First born effect happens when playing one family as well. If you save and exit after having a baby then come back and have another baby you will get first born effect. If you play long enough to give your couple two babies, each baby will be different but if you then save and exit, reload and give them a third baby, the third one is likely to be a clone of the first one as it reset their odds back to how it was to start with. Anytime you go into CAS and roll you have changed the parameters again. If you play long enough to have numerous kids, go often into CAS often or tend to only give couples 2 kids in one sitting or have twins a lot you might not see first born effect happen much to good luck and if it's an opposite gender child whose a clone you could even miss it.

I always figured that was a deliberate design choice, to simulate how college students are sort of in between being fully kids and fully adults.

I confess that I've never understood why there is a "teen voice" at all. I mean, I suppose for game purposes it's a cue that "Hey, this is a teen, not an adult," but to me there shouldn't be that much of a difference between a "teen voice" and an "adult voice." I mean, one's voice changes throughout one's life, due to changing size and thickness and rigidity of the larynx as one ages, but the only huge and fairly sudden change is at puberty, which is obviously especially noticeable in males. So for teens to have a "teen voice" for "years" that suddenly changes dramatically when they hit adult (and again when they hit elder) is sort of odd, and it's always kind of bugged me in a nitpicky sort of way. I mean, I understand that it's really the only way it can be done for game purposes, but it still bugs me.

It'd be funny if older child/young teen males went through that cute (Well, except to the kid himself ) stage where their voice is cracking often as their larynx enlarges...but I imagine that would be difficult for voice actors to do deliberately.

Anyway, just silly nitpicking on my part. I guess it sort of bugs me that teen females get insta-curves yet they have these childish voices that they'll keep all the way through their college years, if they go to college. It doesn't bother me so much with the males.

I turn the sound off when I'm palying. Almost always

And I never had this first born glitch. Playing with one family or skipping around. Never.

For those of you stuck with sibling clones, there is hope. I have downloaded the CharmedBOSLarge, a Book of Shadows that allows your sim, with considerable work, to improve himself, I have these expensive ($999) self-improvement books in my library and in my church. A sim who wants to become neater, nicer or more active can give up some five or six hours to serious study. This means that a teen born of two slobbish parents need not go through life belching and farting. This opens up more options in the game, because you can choose which of the identical siblings will improve, and which will not.

Yes, you have. Because it's not a "glitch;" it's part of the game's programming. Some people are just more apt to notice it than others. Sometimes its effects are subtle, sometimes not-so-subtle. It depends on luck of the draw and the Sims you're breeding. But people have looked at the code, looked at the underlying math, and there's no denying that it happens in everyone's game. It's just a question of whether or not the player notices...or cares, really. Me, I try to remember to randomize but if I forget...Eh, not that big of a deal to me.

There's a mod for that, available here. I find it absolutely stupid and absurd that a child would get out of the shower still stinking like a junkyard to run and hug his/her parents. If I were the parent, I'd much rather my child stay in the shower and finish cleaning up before hugging me and getting my clothes dirty.

I absolutely hate how there are so few interactions for dogs. Seriously, does EAxis even have a dog-owner that does something else other than play fetch and razzle with the dog? I also hate how a teenager who is an enemy of an adult constantly goes over to chat, just because EAxis cut the fight interactions and most of the irritate interactions between teens and adults. Why..... I have no idea why they would do such a thing. I also dislike how kids can't stay home alone (there's a mod for that here), and I also hate how they can't play the guitar. Seriously, EAxis just lost a lot of faith in kids here. Sims 1 children get to play the guitar, while Sims 2 and 3 kids can only watch their parents pluck mindlessly at the strings. Boo!!!

What in the world is that smaller zoom window trying to show me all the time? Absolutely nothing!

Honestly, it's appearance that would bother me far more than personality, with firstborn syndrome. Siblings might be born with the same personality points, but they'll likely end up with different aspirations, interests, hobbies, and, well, life stories - and that makes them unique enough for me, especially if I also use the encourage interaction to change their personalities. It's having physically identical siblings which would bug me, but happily it's never happened to me.

Well, you can change clothes and hair and make-up, and influence fitness or fatness. Changing appearances is not so difficult.

I nearly always tweak the personalities of born in game sims, because I consider that part of the game fundamentally flawed. Yes, you have a genetic personality, but your offsprings personality is still going to be mostly random anyway!

So I push or pull with testing cheats here and there so each trait is within the boundaries of the parents traits. Example: Sim a has 4 nice points, sim b has 8. If the child has 4-8, they stay with what they got, if they got more than 8, I'll drag it down to 8, if they got less than 4 I'll drag it up to 4. It annoys the ever-lovin-crap out of me this whole, somewhere in between OR completely random for each personality trait, until we run out of points!

I also tend to find pacifier rolled or not, my game has a tendancy to randomise high playful nearly every sim born is mid-neat, mid-outgoing, mid-active high playful low nice and a generation into the hood and no one does anything but RPS, or Redhands every second they are left alone.

True, music2, but you can still see quite clearly that the face shape is the same.

I didn't know about firstborn syndrome, or notice it, until I had a Sim pair that was glitched somehow and produced frankenbabies. It was as if someone took the sliders and only let them be at the very extremes, which made no sense since the parents were your average default faces with no extremes anywhere. I killed off the first baby, and the next two ended up the exact same. That's when I found out about firstborn syndrome, and started caring.

But I can see how some people don't think they have it, because depending on how much attention you pay to certain things, you might not notice. I agree it doesn't mean they don't have it since it's hard coded, but I get how one fails to notice it.

Easy, simply randomise before attempting to get anyone pregnant, and if you are afraid they'll DO it without you directing them well...that same saying goes the other way around too : You know how babies are made?
Go into CAS and randomise before entering each household you'll want to play, or use the batbox ( I personally don't have this) jeese...lol
It is so easily avoidable.

Actually, rolling the pacifier when they are trying to get pregnant won't work if you quit the game afterwards. Also, going into CAS before each household would be quite useless

The game resets the genetics subroutine when you begin the session.
So if you play a Simday per round, it's safe just rolling when you load the hood. Right before entering the house with a pregnant Sim about to give birth would do, I mean, there is no point in doing it unless there is a Sim who is already pregnant.
If you forget to do so (happens to me all the time ) and the Sim starts moaning, save, go back to the neighbourhood, roll the pacifier and go back to playing the pregnant Sim.

Well, it's been years I roll/randomize sims in CAS before attempting to get any sim pregnant. Seems to be working fine for me. I have 2 sims which are the exact same sim, except one is male, the other female. They are bro and sis, because I made them (originally, no family links, just a family I *build* using only ONE sim I made and liked, was more a test but turned out fun)
Gudmar just had a child, who looks exactly like him as a toddler. And Beda, Gudmar's fake sis, just had twin girl, who happen to look muchlee like their dad, (edited)Rodney Jung (exported from my previous EA Games files)
Before I ask Gudmar to try for baby with his wife, I went into CAS and randomize.
There are no other baby born between his son, and his nieces.
For Beda, I did the same, and randomized in CAS just before try for baby...not just before birth, before conception.
Since gender of baby is decided AT birth, but the number of babie is set at conception, it was normal to me, that it was at conception that the genes are called..and that if there was randomizingz to do..it would be THEN. Who knows if i am right, important is..I always have babies that looks like their own parents, and that are pretty much unique. Unless i made them the same on purpose.
None of the 3 offspring have the same personality points, astrological signs, or physical shape. I admit though, both toddler twin girls, look alike. But you can see differences in the nose, lips, and eyes.
I changed one girl's astrological sign, so they had the same one..twins ya know.

If there was NO way to avoid FBS, I would shut up..but there is a way, and it is known since a while in the simmer community. If i was experiencing it, it would show..at least a bit!
I am crying FOR identical twins...but if i want them, I must make them myself. Difference.
It's always been this way in my game.

The kids look alike, not the same, though, in my game. They're family, so it does not bother me if they look alike. My adopted children also start to look like their parents, though! I put teen Orlando Centowski through university, he got married, wanted hundreds of kids, so I had him adopted some - and they all looked like him. Not, again, exactly, though. I kind of appreciated that in the game to be honest!

We do, and we know you are not. Genes are called at birth, not at conception. Conception just leads to a pregnancy token that tells you the Sim is pregnant and that the game should go through trimester phases, and how many babies there are (which to be fair, you can change after conception, so not sure that counts either). Everything else is decided when born.

First born syndrome is that the game starts at the same randomized point. Think of it as that the game has pre-tossed dice results in a long list, and every time you close the game it will go back to the same point in the list and start there, which means the results come out the same.

Hahaha that's so funny! And it's seriously annoying too... funny to see a school bus drive off of a cliff

Since you seem quite knowledgeable, how would you explain, if I am not doing what's right, that all my babies, when aging to toddler and up, all look different, all have different personality, predestined hobby, astrological sign ?
If the first born syndrome looks like it looks in my game after i do what i do each and every time..then it stops being a problem..as it also stop being noticeable.
Isn't that the goal?

Randomizing is the key. Before or after I couldn't care less, as long as it is done before the baby is born.
My pictures and explanation weren't enough, then so be it.

It's not that you're not doing it right, Rosebine. So long as you randomize before the first BIRTH of a play session, you're randomized and good to go. It's just that you don't have to do it before conception because the game doesn't give the offspring its genes, personality, etc. until the baby is born. That's what it's doing during that time when that screen pops up that tells you there's a new baby on the way and that the "stork is making sure the knots are tied," etc. Really what's happening during that time is that the game is generating your kid, just as it does when you tell it to generate a Sim in CAS. So, you're not doing anything wrong, like I said. It's just that your timing is a bit off, is all.

@Justpetro: Well, you know what they say about people starting to look like their pets. Maybe with Sims it's that children start to look like their parents. In actuality, I think it's that adoption pool babies are all standard face templates, as are game-generated townies like Orlando Centowski. Many of the templates don't look significantly different from each other -- and probably especially not if you've default-replaced the more extreme Maxis templates -- and there aren't all that many of them. It's born-in-game Sims that have more varied faces, since they're not just a standard template.

I wasn't saying you get first born syndrome, I was objecting to the statement that genes are selected at conception. If they were, exiting without saving wouldn't be a viable method to change the gender of the baby. I seem to recall you saying that conception to birth is almost always the same play session, so in your case, randomizing before conception has prevented it. But for other people that might quit in the middle, it's important they know to do it before the birth. So, your theory is more or less correct, I'm just nitpicky about the details

Maybe some people don't get firstborn syndrome because they've been in CAS and created a new sim between babies. Would that fix it?

Was this problem ever answered? Can't remember, but whatever. There is a mod for this issue, made by Cyjon, and available here.