Here's an article I found ~ written by Florence Clothier, M.D., in 1943. This is an excerpt from "The Psychology of the Adopted Child", The National Committee for Mental Health, Journal on Mental Hygiene., New York.
Did you pay attention to the year? 1943!!
Trauma to Child
The child who does not grow up with his own biological parents, or does not even know them or anyone of his own blood, is an individual who has lost the thread of family continuity. A deep identification with our forebears, as experienced originally in the mother-child relationship, gives us our most fundamental security. The child’s repeated discoveries that the mother from whom he has been biologically separated will continue to warm him, nourish him, and protect him pours into the very structure of his personality a stability and a reassurance that he is safe, even in this new alien world.
Every adopted child, at some time in his development, has been deprived of this primitive relationship with his mother. This trauma and the severing of the individual from his racial antecedents lie at the core of what is peculiar to the psychology of the adopted child. The adopted child presents all the complications in social and emotional developments seen in the own child. But the ego of the adopted child, in addition to all the normal demands made upon it, is called upon to compensate for wound left by the loss of the biological mother. Later on this appears as an unknown void, separating the adopted child from his fellows whose blood ties bind them to the past as well as to the future.
It is pertinent never to lose sight of the fact that no matter how lost to him his natural parents may be, the adopted child carries stamped in every cell of his body genes derived from his forebears. The primitive stuff of which he is made and which he will pass on to future generations was determined finally at the time of his conception. . . The implications of this for the psychology of the adopted child are of the utmost significance.
The child who is placed with adoptive parents at or soon after birth misses the mutual and deeply satisfying mother-child relationship, the roots of which lie in that deep area of the personality where the physiological and psychological are merged. Both for the child and for the natural mother, that period is part of a biological sequence, and it is to be doubted whether the relationship to it’s post-partum mother, in it’s subtler effects, can be replaced by even the best of substitute mothers.
But those subtle effects lie so deeply buried in the personality that, in light of our present knowledge, we cannot evaluate them. We do know more about the trauma that an older baby suffers when he is separated from his mother, with whom his relationship is no longer merely parasitic, but toward whom he has developed active social strivings. For some children, and in some stages of development, this severing of the budding social relationship can cause irreparable harm. The child’s willingness to sacrifice instinctive gratifications and infantile pleasures for the sake of love relationships has proved a bitter disillusionment, and he may be loath to give himself into a love relationship again.’