My Sims 4 Alien Girl Ryoma Became Pregnant...as an Elder?!

So long story short Ryoma an elder Alien sim born from her mother Aeon a Mermaid Sim became pregnant in her Elder Age (Without any mods, cc's etc.) I do not know how it happened or when it occured. I did not control her at the time it happened but all I remmeber is seeing an "Eating for 2" in her moodlet...and I was in disbelief and excitement. In all my years of playing the Sims I never encountered this. She gave birth to her healthy baby girl (Also an Alien) named Atami. FYI her lover is a Human.