Twinning pregnancies?

So you know how they wonder about twin telepathy & them feeling the same pain and all that? My Sims alien twins apparently share pregnancies 😅 for background/context, their mother is human turned spellcaster & their father is an alien. He's actually a twin from another family I created, (I wanted to see if Emit Relevart passed on time traveller traits. He did not 🙄) a twin born from 👽 abduction. Senior Pollination Technician #3 is obsessed with poor Barry & his family 😂 Anyways, when Twilight was pregnant I noticed her twin Rainbow looked pregnant as well. I freaked out wondering when TF she got pregnant & by WHO but when she changed her outfit, the bump went away. She ONLY had the bump in her winter outfit (it was currently winter & was for the whole pregnancy). After Jett was born, Rainbows bump disappeared. Now, Rainbow just found out she's pregnant. I switched to Twilight & she now has a bump but only in her workout clothes 😂 I play on Xbox so I have no mods. I only have whatever the base game, Get To Work, Seasons, Get Famous, Jungle Adventure, StrangerVille & Realm Of Magic has to offer. I have never had this happen before nor have I ever seen this lol