Today, spouses in a registered partnership according to German law have only a limited right to adoption. In spring 2012, the Bundesverfassungsgericht will decide on the constitu-tionality of this restriction. In the scholarly discussion on the matter, the 'natural’ relationship between parent and child plays a central role. This paper looks at the cultural significance and changes of the concept of 'nature' as opposed to 'culture/law' with respect to the legal fiction that is adoption. It shows how the past of adoption law bears on its present.