A 42-year-old Queensland woman has lost custody of her three children after DNA testing revealed the children’s step-grandfather is the biological father of two of them.

Known as “Grandpa” to the children, the 71-year-old fathered the eldest and youngest children of his stepson’s wife during what the Family Court heard was a decade-long affair.

The man’s stepson, who had once believed the children born between 2005 and 2009 were his and who is now estranged from their mother, has won custody of all three.

In a Family Court of Australia judgment, Justice Catherine Carew found while the woman’s husband was not the biological father of two of the children, he had “fulfilled that role since birth’.

The court heard allegations of violence and dysfunction, and that the 71-year-old stepfather while “somewhat of a chauvinist”, “did not consider that he had done anything wrong morally” in fathering his daughter-in-law’s children.

He is also believed to have been responsible for a third pregnancy, terminated in 2011.

The woman, given the court-appointed name of Ms Heston, claimed the pregnancies resulted from her stepfather-in-law raping her.

But Justice Carew found this was untrue, saying there was “considerable evidence” that the relationship was consensual.

The 71-year-old retired European migrant had often spent time alone with his daughter-in-law, they had visited each other’s homes when their partners were not present, had met up in a remote location, and had once spent a night together in a Queensland motel.

The woman had made up a family photo album of her children for him entitled “Memories”.

The man had also attended a pregnancy consultation for the younger child he fathered in 2009 and gone into the examination room with Ms Heston.

Ms Heston, who has two older sons, began living with her future husband - given the pseudonym Mr Norton - in 2002 when she moved from New Zealand to Australia.

media_camera The man, 71, and his daughter-in-law met at each other’s home and once spent a night in a motel together.

Ms Heston and Mr Norton married in 2005, the same year the first of ‘their’ three children were born.

Subsequent DNA testing proved the first of Ms Heston’s youngest three children was fathered by the man’s stepfather.

The second child, born in 2007 was fathered by Mr Norton, a 44-year-old technician.

Ms Heston, who lives on Centrelink and child support payments of $423 a week, suffers from chronic kidney disease and is awaiting a transplant.

She gave birth to her third child - again fathered by her husband’s stepfather - in 2009.

Before they separated in 2014, Ms Heston and Mr Norton had altercations which resulted in the police attending.

In November 2012, a verbal argument over the state of one of her son’s bedroom ended in the couple pushing one another and spitting.

In March 2013, Ms Heston sought and was granted a protection order for herself and the children against Mr Norton.

Sometime after this she called police to complain about his “play fighting” with the children.

However, police found the children “in good spirits and happy and it was determined that no domestic violence had occurred”.

In her judgment, Justice Carew noted that Ms Heston made allegations of repeated rapes and violence resulting in broken ribs and a broken nose against Mr Norton during their 12 year marriage.

He denied the allegations and Justice Carew said she found it “difficult to accept ... her allegation of repeated rapes” because she had also made rape allegations against the New Zealand father of her two older sons.

After DNA tests unmasked the secret of who fathered Ms Heston’s children, both the 71-year-old’s partner and Mr Norton had shown a “capacity for forgiveness” for the older man.

Three separate applications were made to the Family Court for custody of Ms Heston’s three younger children, by her, by Mr Norton and by the 71-year-old man and his estranged partner, who still lives in their jointly owned property.

In ordering that all three children live with Mr Norton, Justice Carew said she did “not consider it to be in the children’s best interests to remain” with their mother. She accepted however that the move was likely to be “traumatic” for the children.

Ms Heston will have access to her children by telephone or Skype, once a week at 7pm, and once a fortnight for up to three hours until May 2019.

Originally published as ‘Grandpa’ was children’s father