I keep track of my Sims' age on a spreadsheet. I am using Nrass to play rotationally and am being very careful to make sure I put the family out of caste rotation when I'm done with them, noting their age. Last time I played this one family, the mom's age was 10 to adult and the dad was 11 to adult. After "checking them out" as @igazor
calls it, verifying their ages and playing them one day, the dad is 10 days to adult and the mom is 17 to adult. I think I can force a birthday on both of them with a cake when the dad reaches adult but why did this happen? What are the possible causes?