(r)=p(G/H1)/p(G/H0)= X/Y. 'The examination of genetic markers within the free fetal DNA (cfDNA) extracted from the expectant woman's blood sample and the DNA isolated from the sample named ALLEGED FATHER reveals genetic COMPATIBILITY, supporting hypotheses of paternity'. The union of XX and XY had resulted in XX expecting little h, but XX and XY were not a couple. XX then decided to give birth to little h independently. Around the fifth month of pregnancy, I discovered that I was XY. Little h was born, but I had no control over that decision. PATERNITY RATIO (r) is the formula indicating the ratio between the probability of being a father and the probability of not being a father. As Jacques Lacan, the french psychoanalyst, used to say, however, 'paternity is always an adoption', meaning that biology – on its own – is not a sufficient condition to live a conscious paternity, not even in the families we define as such. This work, a synthesis of love and ratio, helped me to embrace the revolution I was experiencing.