A dad and a daughter who were estranged for 30 years and began a relationship when they reconnected may have been affected by a phenomenon called genetic sexual attraction.
John Deaves did not spend much time with his daughter Jenny while she was growing up, but in 2000 she went to visit him and his third wife Dorothy in Port Pirie, South Australia.
Jenny, who was 31 and married with children at the time, had only seen her then 53-year-old father three times before her visit.
But within two weeks of the pair's reunion, their relationship evolved into an affair - with Jenny leaving her husband and John leaving Dorothy.
The father and daughter may have ended up together due to genetic sexual attraction, which is described as "the intense physical and emotional feelings that some people experience following restored contact between an adopted person and a close member of his or her birth family."
A study published by Cumbria County Council to offer advice for adopted adults and birth families explains that the phenomenon can happen as some family members feel the need to "touch and smell each other", just as mothers and babies do after birth.
It reads: "The danger, occurs when blood relatives meet as adults without that shared experience, and then try to reconstitute the family relationship without being able to put a familiar label on their emotions.
"The power of attraction can however be so strong that 'normal convention and taboos' become difficult to adhere to even for hitherto conventional and law-abiding adults.
"This level of intensity and desperate need for contact can wreak havoc with existing relationships."
After reuniting and developing a sexual relationship with his daughter, John made a sickening confession to his wife of 12 years.
The woman told Australian Associated Press: "When they got back here he informed me it was the best sex he ever had.
"If that doesn't degrade you I don't know what does. It was my second marriage, and you feel like... you get a very poor opinion of yourself."
John and Jenny went on to have two children together - and the first died shortly after being born.
The couple separated in 2008 after a court ruled they had broken the law. However, they reportedly continued to see each other until the relationship ended in 2009.
Before their split, the father and daughter pair boasted on 60 Minutes Australia of their "absolutely fantastic" sex life.
John even tried to claim that they were a "normal" boyfriend and girlfriend, saying: "Emotions take over, as people no doubt realise, there are times during your life where emotions do rule the heart, it rules the head.
"I knew it was illegal, of course I knew it was illegal but you know, so what."
Jenny also said that sex with her dad was like "a sexual relationship with any other man," claiming the relationship was "not harming anyone else".
Dorothy and Jenny's mum, Joan, had tried to break up the relationship, even attempting to involve the police.
John's third wife told Channel Nine: "We tried to split them up, her mum (Joan) and I did. We tried bringing the law onto them, but they escaped."
The relationship eventually resulted in a court case, with both John and Jenny pleading guilty to two counts of incest.
The first related to the intercourse which led to the birth of their first child who died in 2001 and the second related to the birth of their healthy daughter in 2007.
