The doctor settled back in his chair and chose his words carefully. "Identical twins tend to identify with each other, Mrs. Stanton. There is a great deal of empathy between people who are not only of the same age, but genetically identical. If they were both completely healthy, there would normally be very little trouble in their education at home or in school. Any of the standard texts on psychodynamics in education will show you the pitfalls to avoid when dealing with identical siblings.
"But your sons are no longer identical, Mrs. Stanton. One is normal, healthy, and lively. The other is ... well, as you know, he is slow, sluggish, and badly co-ordinated. The condition may improve with time, but, until we know more about such damage than we do now, he will remain an invalid."
He had been watching her for further signs of emotional upset. But she seemed to be listening calmly enough. He went on.
"That's the trouble with radiation damage, Mrs. Stanton. Even when we can save the victim's life, we cannot always save his health.
"You can see, I think, what sort of psychic disturbances this might bring about in such a pair. The ill boy tends to identify with the well one, and, oddly enough, the reverse is also true. If they are not properly handled during their formative years, Mrs. Stanton, both can be badly damaged emotionally."
"I ... I think I understand, Doctor," the young woman said. "But what sort of thing should I look out for? What sort of things should I avoid?"
"First off, I suggest you get a good man in psychic development," the doctor said. "I, myself, would hesitate to prescribe. It's out of my field. But I can say that, in general, most of your trouble will be caused by a tendency for the pair to swing into one of two extremes.
"At one extreme, you will have mutual antagonism. This arises when the ill child becomes jealous of the other's health, while, on the other hand, the healthy one becomes jealous of the extra consideration that is shown to his crippled brother.
"At the other extreme, the healthy boy may identify so closely with his brother that he feels every slight or hurt, real or imagined, which the ill boy is subjected to. He becomes extremely over-solicitous, over-protective. At the same time, the invalid brother may come to depend completely on his healthy twin.
"In both these situations there is a positive feedback that constantly worsens the condition. It requires a great deal of careful observation and careful application of the proper educational stimuli to keep the situation from developing toward either extreme. You'll need expert help if you want both boys to display the full abilities of which they are potentially capable."