86 R. Bauböck intended and a surrogate mother or an intended father and a sperm donor? Asking the question makes it already clear that the problem is not the multiplicity of citizenships per se, but the mismatch between biologically determined citizenship and parental care arrangements that would also open the door to abusive claims. The traditional solution that is already available in most nationality laws for cases where the biological parent is not the social parent is transmission of citizenship through adoption.5 Why should it not be possible to generalise this model from the marginal case of adoption so that a modified ius sanguinis refers to social rather than biological parenthood (as it already does in several jurisdictions)? The main issue with such a new ius filiationis might be that determination of citizenship is less automatic than it used to be for children born in wedlock to their biological mother and father. Yet states that are committed to the welfare of children have to figure out anyhow how to determine legal parenthood in the more complex family arrangements of contemporary societies. In order to avoid statelessness it is important that every child obtains at least one citizenship immediately at birth. And in order to make sure that children are not caught between conflicting legal norms and can develop stable relations to their countries of citizenship it is important that their citizenship status does not change automatically when they become part of a new family. If these concerns are taken into account through a combination of ius soli with legally determined initial parenthood, what objections can be raised against recognizing primary caregivers as well as persons with additional custodial rights as legal parents who can transmit their citizenship to the child? Don’t abandon the children! Dumbrava’s third argument is that ius sanguinis is not necessary because children’s rights can be protected through other means. He claims that ius sanguinis renders children vulnerable by making their ‘access to citizenship … dependent on parents’ legal status, actions or reproductive choices This is indeed a reason why the children of immigrants need ius soli as an independent right to citizenship in their country of birth. Unfortunately, in the US, their birthright citizenship does not prevent them from being deported together with their undocumented parents, whereas immigrant minors who are EU citizens have a right to stay that protects also their primary caregivers from deportation.6 5 6 See the EUDO CITIZENSHIP Database on Modes of Acquisition of Citizenship in Europe, available at http://eudo-citizenship.eu/admin/?p=dataE UCIT&application=modesAcquisition. Case C-200/02 Zhu and Chen v Secretary of State for the Home Department, 2004; Case C-34/09 Ruiz Zambrano v Office National de L’emploi, 2011.