(3) Admittedly, the legislature is not under a duty always to make the legal recognition of parentage subject to the determination of the biological parents of the child in the individual case (see BVerfGE 108, 82 (100)). In view of the protection of family social relationships under Article 6.1 of the Basic Law and the protection of privacy under Article 2.1 of the Basic Law, it is sufficient to make conclusions as to the paternity of a child on the basis of particular factual circumstances and social situations, above all including an existing marriage, and to attribute legal parentage on the basis of this presumption, if this as a rule results in biological and legal parentage being united in one person (see BVerfGE 108, 82 (100) with reference to 79, 256 (267)). It is the consequence of these provisions on presumption passed by the legislature in § 1592 nos. 1 and 2 of the Civil Code, which are constitutionally unobjectionable, that they may lead to doubts as to the true paternity of a child. But if the legislature decides to follow this legal route of to a large extent not clarifying biological paternity but instead making presumptions, it must at the same time provide a procedure in which such doubts can be clarified in the individual case. The right of a man to know that a child is his biological child, contained in Article 2.1 in conjunction with Article 1.1 of the Basic Law, requires a procedure to be made available for such cases in which the paternity can be clarified without further legal consequences being inescapably attached. This also applies to a man who has acknowledged the paternity of a child. As long as the legislature has not made a procedure to clarify paternity available and does not in addition make the acknowledgment of paternity legally dependent on the proof that the child is the biological child of the person acknowledging paternity, a man may only base his acknowledgment on his presumption, supported by statute, that he is the father of the child. In doing this, he has not forfeited his right to know that the child is his biological child if doubts later arise.