(Following up on my previous post)
Okay, I had tried tweeking the aging options only to active family... but I must have flubbed it up.
When I returned to the original lot, all the infants I left behind had grown into Adults and were already halfway to Elder. They were all completely undeveloped/underdeveloped with no skills or traits to speak of. All characters older than teenagers at the time I had left this lot had all died of old age and neglect. There're no urns or tombstones to provide a ghost of a chance to recover those characters. I guess they've been culled from the game?
The most developed character I left behind was "Brandon." The only evidence remaining of his existence were his childhood pictures. He was on his way to becoming a great artist... but it's like he never was.
This is quite disheartening. "Urgh!"