" young children, who for whatever reason are deprived of the continuous care and attention of a mother or a substitute-mother, are not only temporarily disturbed by such deprivation, but may in some cases suffer long-term effects which persist
Bowlby, J., Ainsworth, M., Boston, M., and Rosenbluth, D. (1956). The effects of mother-child separation: A follow-up study. British Journal of Medical Psychology, 29, 211-249. "

― John Bowlby