De-aging My Sims for greater story continuity

My Sims couple finally graduated their son from high school (woohoo!), and he is now out on his own as a young adult. The trouble is, as soon as their son aged from teen to YA, my Sims just aged into their "senior years." I think the age continuity is off, so I went into cas.fulleditmode and aged them back down to adult status. In my mind, their son just turned 20, so they can't be more than 45 themselves. 45 year-olds should not (despite what some younger people think) look like 60-70 year olds. I know there are mods to manage the aging, but I am trying to keep my game as "mod free" as possible. Anyone else use the cas.fulleditmode to manage their Sims aging?