I actually was diagnosed with inhibited RAD as a child, and schizoid personality disorder as an adult. Both disorders involve a profound lack of affective emotions and empathy. I do not cry, almost ever. The only times that I have cried as a grown-up have been a result of dissociative fugue/switching, and after psilocybin therapy. My therapist suspects a lot of this was trained out of me in childhood, due to the extreme actions that occurred whenever I did cry. When babies cry and it is ignored, it's typical for that infant to stop crying, so that it doesn't expose itself to predators. Since the infant realizes that it is alone and not amongst family members who will respond.
There's a lot of interesting evolutionary psychology at play, there, but it speaks to the linearity of disorders like RAD. Again, not to make it about myself, as I often do! (Ha, +1 for that autistic thinking) but just to throw another example in the ring as to how profoundly hormones can actually impact a person. My mother was simply not an asshole. We have a good relationship now, and she has taken responsibility for her behavior in my early childhood.
She is a good person, who ended up becoming psychotic due to post-partum hormones, and who had no assistance of any kind other than her equally mentally ill (NPD, abusive) mother. I've forgiven her, but obviously, this is because I lack the emotional capacity to feel abandonment/betrayal/etc. It might be different if I had access to those feelings, but I am content with it all. I feel at peace with our relationship, and I would not relish having to re-process it all through those emotions.
It simply isn't important to me to force that state on myself, to work through something that I've already come to terms with. But another child, who has a different reaction to post-partum psychosis, who maybe does end up with some emotions intact? That is going to be a long road to peace between mother and child, for sure.
like people say that but what do ya do about it 
