The front yard to number 160 was often overgrown. When the pale children were spotted in Muir Woods Road they tended to avoid conversation.
Now the neighbours know why.
The alarm was raised only on Sunday, when a 17-year-old girl escaped from the family home. She used a cell phone she had found there to call emergency services.
When they arrived at the single-storey house in a modern development in California, authorities found another 12 of her brothers and sisters in varying states of distress. Some were chained to beds and some were malnourished, the police revealed, as they described the squalor inside. Investigators said the teenage girl who had raised the alarm she was so under-sized that they took her to be ten years of age.
David Allen Turpin, 57, and Louise Anna Turpin, 49, were arrested on Sunday and each charged with nine counts of torture and 10 counts of child endangerment.
“Further investigation revealed several children shackled to their beds with chains and padlocks in dark and foul-smelling surroundings, but the parents were unable to immediately provide a logical reason why their children were restrained in that manner,” said a statement from the Riverside County Sheriff’s Department.
Officers were shocked to discover that seven of the 12 children found in the house were in fact adults, ranging in age from 18 to 29. They were so emaciated that they had the appearance of children. The youngest of the 12 is aged only two. "The victims were provided with food and beverages after they claimed to be starving," said the sheriff's department.
Neighbours in the small community of Perris, about 95km south-east of Los Angeles, said they were shocked to discover what had been going in the detached home where three newer model Volkswagen cars were parked out front.
Kimberly Milligan, 50, who lives across the street, said she had rarely seen the family. Since moving in two years ago, she had only once seen a baby in the mother's arms and three other children, describing them as small and pale.
"Why don't we ever see the kids?" Ms Milligan said. "In hindsight, we would have never thought this, but there were red flags. You never don't hear or see nine kids."
She described how she complimented three of the older Turpin children on the nativity display outside their house one Christmas but they froze as if trying to become invisible.
“Twenty-year-olds never act like that,” she said. “They didn't want to have a social conversation.”
Their Facebook page presents a portrait of a happy, loving family. One shows the gathered brood wreathed in smiles during a visit to Disney World in Florida. In another, they stand before a hilly backdrop, with the siblings all wearing “Thing” T-shirts from the Dr Seuss book The Cat In The Hat.
The girls all have a similar haircut as do the boys, their hairstyles matching those of their parents.
A set of pictures shows what appears to be a wedding ceremony, with one of the boys acting as ring bearer to his parents. It was in fact a wedding vow renewal ceremony in Las Vegas.The girls are all in matching plaid dresses and an Elvis impersonator officiated.
State records show the children were homeschooled. The California Department of Education lists Mr Turpin as the principle of Sandcastle Day School, a private school operated from his home address. It says six pupils were enrolled there.
The children’s grandparents said they had been subjected to strict schooling and were expected to memorise long passages from the Bible. James and Betty Turpin told ABC News they had not seen their son and daughter-in-law for several years but stayed in touch by telephone. They were shocked and saddened by the revelations regarding their grandchildren and explained that “God called on them” to have so many children. It is unclear whether those are the beliefs of James and Betty or if they were quoting what David and Louise had told them.
Public records also show that Mr Turpin was declared bankrupt in 2011. At the time, he was working as an engineer for Northrop Grumman, a global defence contractor, where his salary was $140,000 a year.
A lawyer who represented the couple told the Los Angeles Times newspaper that the couple struggled to make ends meet with 12 children at the time as their outgoings exceeded Mr Turpin’s income by about $1000 a month.
"To me and my wife, Nancy, who was with me during the interviews, we always thought of them as very nice people who spoke highly of their children," said Ivan Trahan. "They seemed like very normal people who fell into financial problems."
That still leaves a community left with its soul searching. Neighbours gathered on the pavement outside their modern, stuccoed homes to discuss the handful of times they had met the family.
Nicole Gooding, 35, who has lived in the neighbourhood for three years, said that the first time she saw the family was two months ago when the mother and children were cleaning up a front yard filled with weeds and overflowing rubbish bins.
“I had never seen them at all until that day,” she said.
Others described a similar scene with children laying turf at night under floodlights as their mother kept a watchful eye over them. One neighbour, Gary Stein, described the scene as "weird" but did not think it was his place to interfere.
No details have been offered about the parents' alleged motives for holding their children in such conditions. They couple are scheduled to appear in court on Thursday and are being held on $9 million (Dh33million) bail.