It's just when they are at the beginning of each stage that it is weird. Bella being at day 1 of YA while Cass is at day one of teen is weird. But in my game I give every YA/Adult a potion of youth halfway through, so that they age to adult at what is closer to mid-forties, and to elder at 69, so they stretch out more. I always give my Adults a slightly more middle aged look.
In my game, Cass aged to Adult about 10 days before Bella ages to Elder, which makes them close to 20 years apart.
In real life, most of my friends from high school either had kids by 21 or not until over 30, so some are grandparents in their 40s and some are still parenting preteens or younger.
