Regardless of whether he is the biological father or not, a man who claims a child born to a single mother as his may be legally recognised as such. All he has to do is sign an Acknowledgment of Paternity (Reconnaissance de Paternité). Even if he is the biological father, and the mother is in agreement, he still has no legal standing as a parent until he has signed the Acknowledgement.
According to Article 226-28 of the Penal Code, unless ordered by a court of law, DNA and paternity tests are illegal; people breaking this law risk a €15,000 fine and/or imprisonment for up to 12 months, even if an overseas laboratory has been used.
In addition, the Bioethic Law of 29th July 1994 prohibits people using non-officially sanctioned clinics in order to have a baby via sperm donation. Parents found guilty of this – and again, foreign clinics are barred – are liable for a €30,000 fine and 24 months in prison.