Old looking toddlers?

People always complain about old teens but I thought since forever that all of the ages below young adult look old for their age. Or their supposed age. You can get teens to look younger fairly easily but that's mostly only with the right cc and cc presets. I've always assumed it's just the artstyle but younger sims don't have enough distinction in their faces. Hard to describe but it's obvious by looking at them something is missing.
That's why I'm disappointed that the majority of the cc skins people made for infants are just converted kid skins and the infants look even older as a result. An infant and a kid that age looks nothing alike in terms of youngness.