Anxiety Disorders: Mental Illness or Normal?

Generalized anxiety disorder, OCD, social anxiety disorder (social phobia), PTSD, panic disorder... The current worldview of these problems is driven by the medical model and the belief that they are (mental) illnesses caused by something going wrong in our brain and that the answer lies in 'fixing' the thing that has gone wrong. However, take the man in his early twenties, whose father constantly put him down and criticized him with such venom as a child that he's now petrified others will do the same.
is his (social phobia) thinking really dis-ordered? Has something simply gone wrong in his brain?...or is there a better explanation? And a better solution?