Their birthday was the same day yes, but they shouldn’t have aged up because it usually takes a full day without aging them up after their birthday for them to auto age (at least to what I set my game to. I could be wrong about this so let me know). But the adult for certain did not have the age he has now. It definitely made his life longer all of a sudden. Since like the average age for an adult in a normal life span is 24 days and he was an adult in my game for about a week, but now has 23 days. The birthday significantly moved and I’m pretty sure it was because of the bug. However if you think it’s something else let me know what I can do.