It is widely assumed that there is value in the biological tie between parent and child. An implication of this is that adoption is often considered a less desirable alternative to procreation. This paper offers a philosophical defence of adoptive parenthood as a valuable and authentic form of parenthood. While previous defences have suggested that society’s valorisation of the biological tie is unjustified, I argue herein that the conception of the biological tie that features in the normative discourse on parenthood (...) is too narrowly genocentric. Against this genocentric conception, recent work in the philosophy of biology has emphasised the roles of joint determination, dynamic construction, and extended inheritance in development, which I suggest can substantiate a more inclusive conception of the biological tie. Accordingly, I propose that adoptive parents form a rich variety of biological ties with their children, some of which are as heritable and formative as genetic relatedness. (shrink)