Некоторые из ранних классических исследований усыновления: L. L. Heston, “Psychiatric Disorders in Foster Home Reared Children of Schizophrenic Mothers,” Brit J Psychiatry 112 (1966): 819; S. Kety et al., “Mental Illness in the Biological and Adoptive Families of Adopted Schizophrenics,” Am J Psychiatry 128 (1971): 302; D. Rosenthal et al., “The Adopted-Away Offspring of Schizophrenics,” Am J Psychiatry 128 (1971): 307.