Believe I read and heard some stuff (but forgot where) about that
there are a lot of axons made in months after birth and that then many
of those not used enough get reduced, and that there are case of
having like a third less brainstuff in neocortex areas in some very
young children who were neglected too much in a form so that that
happened.
IMO in emotion generator programs bad secondary programs and
alterations of primary ones can cause psychological problems later on.