Jimmy had a good life and an important job as a print-works manager. He was high up in the local freemasons and had many friends. Everybody liked Jimmy. His second wife, Patricia, used to complain that he worked too hard, being in the office all hours at evenings and weekends, but the fruits of those labours were obvious to his sister.

There were things she wished she could talk to her brother about, but never felt able to, not while her father was still alive. There had never been much talking in their family. As she said, there could have been a pink elephant in the living room of their childhood home and nobody would have mentioned it.

Predictably, when she had ventured an opinion two years ago, saying she could no longer look after their father because she was too busy looking after herself, it had resulted in a distance opening up between her and Jimmy. She was sad, she still loved him, but she needed to put herself first for once, as she tried to get back on her feet following a long period of heavy drinking after the sudden death of her husband.

She had never seen the lovely new home Jimmy had moved into with his family. But they were still entwined: she was always the black sheep, Jimmy the blue-eyed boy, brother and sister bound together by their past and, of course, their shared genetic make-up.

When Detective Sergeant Sue Hickman from South Yorkshire police knocked on her door in March this year, the woman was initially amused. Was it something from her drinking days? Something she had done and not remembered? Well, yes and no. DS Hickman was investigating some serious crimes from years ago. She gave a reassuring explanation about how it was like those cold-case programmes on the television. There was the possibility – only a possibility – that she might have a brother who needed to be eliminated from the inquiry.

The possibility resulted from the DNA sample she had given in 2000. Her DNA had been loaded onto the national DNA database, where a “familial search”, using the latest advances in technology, had shown that it bore similarities with the DNA left at the scene of those 20-year-old crimes by the male perpetrator.

She did not much like being reminded of the time she had given a DNA sample. It would later be widely reported that she had been caught for drunk driving, but that was not quite the correct story. At the time of her arrest she was sitting in her car on the grass verge of a roadside near her home, a bottle of vodka in one hand and a mobile phone in the other. She had gone there to be alone so she could call the police, the vodka giving her “Dutch courage” to report the terrible thing that had happened to her the night before.

She had been raped by someone she knew. The police would eventually talk to her alleged assailant, but she would not go through with a prosecution, and the man was never charged.

As yet, she had no idea of the appalling irony involved in the fact of her rape. The police had come out that night, perhaps for her own protection as much as anything else, and found her in the car on the verge and breathalysed her. She had returned to the police station a week later to be charged with being drunk in charge of a vehicle, and it was then that her mouth had been swabbed for DNA. She later recalled how Jimmy had seemed uninterested in what had happened to her when she told him, only asking if she’d had her DNA taken. At the time, his indifference seemed insignificant. She first thought DS Hickman could be looking for her half-brother, born in the middle of her parents’ marriage after her mother had, as her daughter put it, gone looking for love elsewhere when she couldn’t find it with Desmond, her drunken and abusive husband. Desmond had refused to allow the child into their home, so the baby boy had been adopted. She had never seen him again, never even knew his name. Her mother, Sylvia, had died 20 years ago from cancer. She had been a gambler, playing slots and bingo, the children often coming home from school to an empty house with no food for tea.

But it was not the half-brother DS Hickman was interested in. He was too young. The offences had occurred in the mid-1980s and the offender would have been in about his late twenties. Well, Jimmy would have been that age; he was 50 this year. DS Hickman told her she would contact Jimmy to invite him to give a DNA sample. When the officer had gone, the woman called Jimmy at work, light-heartedly reporting that the police would be in contact. Jimmy gave nothing away in his response. Okay, thanks, he said. But almost immediately, he walked out of work. She had a call from her father about an hour later. Jimmy had called him to say he was going to kill himself because of a crime he’d once committed. Her father was upset, but she pressed him. What did Jimmy do? He’d raped someone, in the 1980s. And not just one person. Jimmy was a notorious serial assailant, the Dearne Valley shoe rapist, who had attacked at least six women, almost certainly more, from 1983 to 1986, and stolen their high-heeled shoes.

Even though she was not so far apart in age from his victims, and even though she lived in the same area of Rotherham, she had never heard of the Dearne Valley shoe rapist or his crimes. Maybe that was not so surprising. Her life was turned inwards, often a matter of survival.

When she finally found out who her brother really was, she at first felt guilty. She blamed herself. What would Jimmy think of her? She had grassed him up. After all, it was her DNA that trapped him. Of course, she was not thinking straight. The anger and disgust at what he had done came later. But she was right – he had evaded capture for 20 years and might otherwise have gone on living his regular-ish way of life for the rest of his days. DNA had ended all that. His capture was in large part a tribute to the determination of the police, but it was also a “miracle” of modern science.