I tried finding this but could only find [Old / Obsolete] threads that didn't really fit.
What happened was I had a sim born in game as male, when they turned teen I decided to try something different and turned them into female with male pronouns instead of just using a female frame on them. I kept it because there was less weirdness in the neck seams.
However, instead of being referred to as male consistently, it's about half and half. CAS relationship tabs list him as a "Sister" (screenshot provided from his sibling's CAS tab), phone calls from siblings not in the active family refer to him as "Sis" (especially the meme-sharing one). The family tree lists them as "Sister" (screenshot provided) as well as listing their Skill-Mastery Perk (Skillfull Sleep) perk ghost as their own entity, as a "Sister", and Deceased: Temporary Specter (screenshot provided and the sim in question is awake / not using Skillfull Sleep). Most flavortext is right and uses male pronouns. The flavor-text when he reached 5-star celebrity used both (screenshot provided).
When I removed mods for testing all of the sims had the household relations unselectable with the notification that you cannot change pre-existing households. All related household members had this sim listed with female pronouns in the household relations tab in CAS.
