ON A rough block of scrub hidden in the hills above a quiet NSW country town, the Colt family had a terrible secret.

Living in a row of ramshackle tents and sheds which had no showers, toilets or running water were 40 adults and children. But the Colts kept to themselves.

Neighbours on one of the large properties or hobby farms occasionally heard a chainsaw, but no laughter or play.

The men occasionally sold firewood and two of the adult men worked as council labourers.

Occasionally, the womenfolk would come into town in a four-wheel drive.

Out would pile a dirty troupe of ragtag children, some of them rail thin, wearing dirty clothes.

The town people didn't even know their names.

Occasionally, when the welfare officers came visiting, the children would be forced to attend a few days of school, where they needed remedial teaching.

It wasn't until a squad of police and child protection officers arrived unannounced on the property one day in early June last year, that the shocking truth about the Colts would be revealed.

DEPRAVED SECRETS IN A COUNTRY TOWN

Not only were the Colt family closely related by generations of incest. In fear of discovery the appalling facts about their family, the Colts had fled three other Australian states before coming to rest in rural NSW.

And it was here that four generations of interbreeding exploded into a life of depravity.

Under the eye of the family matriarch, Betty Colt, who slept in the marital bed with her brother, the children copulated with each other and with adults.

Years of interrelations had resulted in some of the children misshapen and intellectually impaired. Many of them could not speak intelligibly.

They were profoundly neglected, to the point they didn't know how to shower or use toilet paper, and were covered in sores and racked with disease.

Left to their own devices, brothers with sisters, uncles with nieces, fathers with daughters, they engaged in sexual activities.

The children also mutilated the genitalia of animals.

When the girls became pregnant, they would often simply miscarry on the farm, not wanting to arouse suspicions among doctors or health professionals.

While the Colt women claim outsiders had fathered their children - itinerant men, a wheat worker, a Swedish backpacker - science told otherwise.

When they finally managed to get test swabs into a laboratory, geneticists uncovered a family tree which was a nightmare of "homozygosity", when a child's parents are closely related.

Eight of the Colt children have parents who were either brother and sister, mother and son or father and daughter.

A further six have parents who were either aunt and nephew, uncle and niece, half siblings or grandparents and grandchild.

Interviews with the Colts revealed the family saga began back in New Zealand, in the first half of last century when June Colt was born to parents who were brother and sister.

June married Tim and in the 1970s the couple emigrated to Australia.

The family would then move, several times, between South Australia, Western Australia, and Victoria, usually living in remote rural communities, shying away from public knowledge about the truth.

Tim and June gave birth to four daughters and two sons.

Three of the daughters - Rhonda, 47, Betty, 46, and Martha, 33, and at least one of the sons, Charlie, form the elder members of the family group in the NSW bush camp.

Betty had 13 children.

She contended their father was a man called Phil Walton, now dead, who was known to the family as Tim.

But genetics show one of her children, Bobby, 15, was fathered either by her father, whose name was Tim, or the brother she was sleeping with.

Four more of Betty's children were fathered by a close family member.

Betty's eldest child, Raylene, now aged 30, has a 13-year-old daughter, Kimberly.

Raylene insists Kimberly's father is a man called Sven, from Sweden or Switzerland.

Testing identifies Kimberly's father as either her half brother, an uncle or a grandfather.

Betty's second oldest child, Tammy, now aged 27, has given birth to three daughters, one of whom died from a rare genetic disorder, and all of whom, she eventually admitted, were fathered by her closest brother, Derek, 25.

Betty's younger sister, Martha Colt, 33, has five children, four of whom were fathered by her own father, Tim, or by her brother, and another who is the product of a union with a close relation.

It was the 10 youngest of Betty and Martha's children, and Raylene's daughter, Kimberly, 13, who ran wild in a sexual spree about the property.

Betty's children, Bobby, 15, Billy, 14, Brian, 12, Dwayne, 9, and Carmen, 8, all have parents who are close family members.

Martha's children, Albert, 15, Jed, 14, Ruth, 9, and Nadia, 7, are also the product of closely-related parents.

Interviewed by child protection workers and psychologists, they told of a virtual sexual free-for-all.

Ruth and Nadia said Albert, Jed and Karl showed them pornographic magazines, touched their breasts and Albert had sexual intercourse with them.

Kimberly said she had oral sex with Dwayne, while Carmen watched. Her mother Raylene had been aware of the incident.

Albert, Jed, Karl, Bobby and Billy admitted they tortured animals, including puppies and cats. Carmen said her father was her uncle Charlie.

Ruth said her father was Charlie. She also said her brothers, Jed and Karl, had sex with her.

Following the discovery of the Colt family in the hills, 12 children have been removed from their parents.

Their mothers have hired lawyers to argue in the courts for the children's return.

One of the mothers is due to face court on charges of procuring the removal of a child from care and recruiting a child for a crime, and further charges are expected.

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