Partnered Sims turn into siblings

This had happened to me as well in the update! My sim Nakoki had (now deceased) parents and for some reason my other sim Johnnie who is Nakoki’s husband is seen as a brother to his husband and a child to the parents and they are supposed to be seen as a son in law to the spouse’s parents. Not only that my sim Nakoki is also divorced to his ex wife Miwa who had only 3 children together before they divorced and for some reason she is not in the family tree as divorced in that sim’s pov. The ex also used to married to another guy and they had twins before they were divorced as well and when I checked the family tree she was in it but in her family tree she does not recognize her first ex Nakoki or her other kids as family same with the half siblings. I never in my years of playing the sims had ever experienced this type of bug before! And I heard people dealt this many months before this update came out. Edit: I found out it is because they are the same sex which is why the game believes they are brothers but that what makes the situation even more ridiculous because how come it didn’t affect the other gay couple from cats and dogs? Genuine question…

Happened to me as well! Scary as it's identical to the old (old but currently unfixed) Get to Work bug where cloned sims become siblings to their spouse as well. Save File Ruiner because it's unfixable even with MCCC or uploading to gallery. 

My guess? An issue with "sibling-in-laws" incorrectly being tagged as "siblings" in the game. If your spouse's sibling is your sibling, then your spouse gets tagged as also being a sibling. 

See: Frida + Ulrike are CAS siblings with no parents. In addition to Ulrike's erroneous tagging, Frida should also be tagged as "sister-in-law", but she's tagged as "sister" instead. This is my guess as to the origin of the issue. 

Can confirm this has also happened on my sim's family tree, as you can see Suzu is my founder's wife, they have children together, yet she's now being marked as her sister via an unknown parent. Interestingly Suzu has a sister, which lends credence to the idea that it could be sister-in-law causing the bug, however further down the family tree I have both straight and M/M couples who have in-laws that are not being marked as siblings, so it doesn't seem to be consistent.

Edit: to add info to this; I am playing with mods/cc, I have not tested it without them as I'm hesitant to load the save without mods. I do not believe I have any mods that affect family relationships.

same!!!!!! please help it's making me so uncomfortable

same!!!!!! please help it's making me so uncomfortable

happened to me this evening! my sims both had separate assigned parents, are married with kids, and randomly got updated to half-sisters. it auto unassigned one of my sims parents from the family tree. i’ve updated the relationships, but can’t get rid of the ‘unknown’ sim link to fix the tree. 

This happened to me today too. Please fix this asap. 

I only play female sims and was playing rotationally with my eldest characters, one of them accidentally died and i brought her back to life.

I think the root cause is what the other posters are saying. They didn’t have that unidentified parent above before.

I’ve never used mods or CC for that matter. Since I don’t use mods, is this family tree forever broken?

Please make the fix so that it’s fixable for current save files. 😣

MY Sims that have 3 children together are now considered family as being a cousins child.  I really wanted them to have more children as they are the only blonde sims left in my game. My family tree is so large as I am on the 12 generation and everyone in town is distantly related. I also have two random sims that should be in a different family tree that somehow became brother and sister to some other of my sims. It's getting all so confusing that I am only allowing each sim to have but one child now. I play rotationally so the family tree is very important for me to keep track of who's related to who.  Ack I really hope this gets fixed as soon as possible.

This has happened to my Very Veggie legacy sims too! Very frustrating!

literally!! it’s pissing me off so bad , they heed to fix it immediately.