The common view of adoption in pre-Islamic times is that it was widespread, that adoptees were the legal equals of biological sons, and that the institution was abolished with the advent of Islam. In the first part of this study I question the first two of these views. In the second part I argue that adoption, acknowledgement of paternity and false genealogical claims are three distinct practices, although scholars often confuse one with another. I explain the differences between them, and identify the sources of the confusion. Finally, I briefly mention Islamic alternatives to adoption.