Tell through the instruction manual and story, ubless they were all babies having babies. Cyan's concept art makes him look at least 40.
Most of the characters were dealing with a loss of family.
Locke: dying lover
Terra: Loss of parents
Sabin and Edgar: Loss of father
Relm: has a deadbeat dad
Shadow: IS that deadbeat dad
gau: abondoned by father
Cyan: loss of wife and children
Exceptions are Celes, Mog and the airship guy, and the two extra characters.