Is It Right Not To Punish?
From Q and A in Child Discipline By James Dobson (1976)

I'm afraid you are making a mistake commonly committed by the parents of adopted children. They pity their youngsters too much to control them. They feel that life has already been too harsh with the little ones, and they must not make things worse by disciplining them. As you indicated, there is often the feeling that they do not have the right to make demands on their adopted children. These guilt-laden attitudes can lead to unfortunate consequences. Transplanted children have the same needs for guidance and discipline as those remaining with their natural parents. One of the surest ways to make a child feel insecure is to treat him as though he is different — unusual — brittle. If the parents view him as an unfortunate waif to be shielded, he will see himself that way too.

Parents of sick and deformed children are also likely to find discipline harder to implement. A child with a withered arm or some non-fatal illness can become a little terror, simply because the usual behavioral boundaries are not established by his parents. It must be remembered that the need to be controlled and governed is almost universal in childhood; this need is not eliminated by other problems and difficulties in life. In some cases, the desire for boundaries is maximized by other troubles, for it is through loving control that parents express personal worth to a child.