I think that part of the reason that she can be and is that gentle with them is that she's been taught, through demonstration, that these are items with which we take great care. That's not true for all children.

Basically, I think when you say "If J can, so can other children", you're leaving the sentence unfinished, and could be completed as "If J can, so can other children whose wonderful parents have taught them to be conscientious."