A DAD groomed his two daughters for sex from the age of eight - then spent years repeatedly raping them, getting them pregnant a total of 19 times.
The 56-year-old dad lived in a Sheffield housing estate but cannot be named to protect his victims and their children.
He committed the shocking abuse over a 30-year period, fathering nine children with his daughters, Sheffield Crown Court heard.
Two died on the day they were born and the other babies were lost either through miscarriages or abortions.
The dad pleaded guilty to nine rapes and two indecent assaults against his elder daughter, and 16 rapes and two indecent assaults against her younger sister.
The abuse was carried out between October 1979 and February this year.
He denied an indecent assault against each of them, as well as a rape against his younger daughter, when they were each aged under 10. These charges will lie on the file to spare his victims the trauma of a trial.
Nicholas Campbell QC, prosecuting, said: "These charges represent a course of conduct and these pleas of guilty embrace the causing of 19 pregnancies - seven to his older daughter, and 12 to his younger daughter.
"From these pregnancies there are seven children alive today. Two children died on the day they were born, there were many miscarriages, and several abortions when clear disabilities were found upon screening.
"The seven surviving children each have their own difficulties - two of them are very severely incapacitated, and one has been diagnosed with a fatal condition."
The man accepted he was the father of the nine children and was "probably" the father of the remaining unborn children. Recorder of Sheffield Judge Alan Goldsack QC said: "He accepts grooming them from pre-puberty, and raping them from then through until their 30s."
James Baird, defending, said a psychiatrist's report showed the man was not suffering from any mental illness. But the case was adjourned for sentencing so reports and other evidence could be put before the court.
Mr Campbell said this would include medical evidence about the poor health and quality of life of two of his most ill children, as well as a geneticist, and the involvement of social services.
He said: "It seems clear from the medical evidence that the mix of the DNA of this particular defendant with that of both of his daughters from very early days showed that damage would be caused to their off-spring.
"After that damage became obvious, he still went on impregnating his daughters."
The man was remanded in custody until Tuesday November 25 when he will be brought back to court for sentence.
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