Not sure if there has been a talk about this here yet but starting this thread to hear some opinions and experience with this issue.

About the issue: Your sims get a child and you don't like the genetics so you want to change, let's say, the hair color, eyebrows, eyes etc. (via cheats of cas.fulledit mode) but no matter how you try to alter your sims, those changes keep returning to what ever they were originally or just randomize to something else. This mostly happens with CC games only.

I've been searching about this for couple of days and so far I've learnt that it has a lot to do how the game is programmed to hold the genetics.

Quoting: Writin_Reg of The sims 4 forums: "You may not be using any CC for him but it does not mean his sim is not affected by the CC his parents may have. Genetics could be part of the issue seeing the programming is already in that sim to grow up and possibly have the same things his parents have. Like if they have CC hair - the game is compelled to give the kids the same genetic compounds like hair and eye color the parents have - but if there is no CC hair in that CC for kids - then the game is just going to keep changing your sims hair as it cannot match the parents hair and is programmed to match it."

Also there has been talk that this issue started since the recent patches (?).

So what's your experience on this?
Has this happened you without CC?
Does this only happen with your sims children or with others?

If this is only CC related issue does any of you think this can be fixed eventually? I usually like to change my sims' appearance and not be bound by the genetics like I did in ts3

This has happened to me only with default replacements that didn't have all ages checked. The game will then reset the sim to how it was, or randomly pick something else.
With Sims 4 Studio you can open a package and check if this is the case.

It's always been my understanding, that if CC is based on a Maxis mesh and/or texture, then no matter how different the CC is from its parent Maxis mesh/texture, the game will automatically default to the Maxis mesh/texture so that offspring can come out looking very different form parents who have CC. Made even worse when a talented creator makes a completely new, unique mesh and new texture unlike anything Maxis have provided, so-much-so when creating a newborn's genetics, the game by its design can only search Maxis meshes and textures for a genetic match, to make a completely alien looking child from the unique CC of the mother and father.

If memory serves, there were mods for previous sims games to help the game make a better genetic choice based on unique CC, but nothing like this exists for TS4 presently, so it's going to be a hit-and-miss, mixed bag of pot luck, as the game scrabbles together Maxis resources to define offspring.

Having said that, it is strange that taking offspring into cas.fulleditmode and the cosmetic or genetic changes still don't stick afterwards. That's new, I thought that would work. It used to, didn't it?

Just a thought, but are the sims you're trying to change also have alien genetics? I've not actually tried to change alien genetic sims in TS4 cas.fulleditmode, but if it's anything like TS3, I remember the rigmarole trying to change things like werewolves who had two sets of genetics as it were, and how often my changes were reverted as they had "two" genetic versions of themselves and changing only one never stuck. Ahh, just a thought.

No, no Aliens. I haven't yet even figured out how to play an alien, lol.

anyways, I never experienced this before last week after not having played sims 4 for about 5 months - so 5 months back I had no such issue (yet I owned the same cc, no more no less). I had played 3 generations and altered all my kids genetics with cas cheat successfully.
But then last week for the first time when my sim couple had triplets and I went to cas.fulleditmode to change their eye colors (only having 1 set of default replacement eyes that in my knowledge is enabled for all ages) but the cc eyes kept resetting to EA eyes. After trying long enough the cc defaults decided to finally stay on the one of the kids, but during the game play they eyes began to change colors.

Once I got tired of this issue, I removed every bit of cc. But each offspring's eye colors kept changing even with my cc free game. I came to conclusion that my save files were borked so no mod removing would save it.

I decided to create a brand new sims 4 folder and start a clean game with bran new sims. I added different type of cc this time. Yet the moment when my new sim got a child, this one too began to experience the same issue.

It's just so odd how the game is programmed to keep the genetics so stubbornly, unlike sims 3. Guess it's a good thing... but not for a cc gamer who isn't satisfied with genetic outcomes

I know that after the dreaded March patch to make ready for GTW, the worst hit CC items were default skins and eyes. A lot of stuff got broke. A helpful list was made by the community to highlight some of that broken CC. It's worth checking here - http://www.modthesims.info/showthread.php?t=551495 - to see if your default CC eyes might be on that list.

Thanks, I'll check it out

edit: Just opened couple of cc in s4s and deleted all the swatches except the one I wanted for the sim. Try to change the color of your darn hair now you stupid kid! Success.

Yeah. I notice that sometimes I can't change the eye color of my kids though it hasn't happened much. To play as an alien go into cas and click add a sim. You should get 4 options genetics, make an alien, pull from gallery and make a sim. You pick make an alien and boom alien.

With debug cheats, you can add or remove the alien trait to any sim in a jiffy. Insta-alien, or vice versa, whenever the mood takes you...

Moving to Help.