The parents of 13 siblings who were allegedly held captivity in their family's California home have been charged with torture and abuse.

It is alleged that David Allen Turpin, 57, and Louise Anna Turpin, 49, committed years worth of torture and abuse, leaving their children malnourished, undersized and with cognitive impairments.

Some 12 counts of torture, seven counts of dependent adult abuse, six counts of child abuse, and 12 counts of false imprisonment have been made against the couple.

David Turpin was additionally charged with one count of a lewd act on a child under age 14.

The couple's children range in age from two to 29, but the torture and false imprisonment charges do not include the two-year-old.

Announcing the charges against the couple, Riverside County District Attorney Mike Hestrin, referred to the alleged crimes as "severe, emotional, physical abuse... this is depraved conduct".

Mr Hestrin added that the couple kept their children chained as punishments.

The couple's actions came to the attention of authorities after their 17-year-old daughter climbed out of a window on Sunday and called 911 on a mobile phone.

The teenager said she had been plotting her escape for two years.

Another sibling escaped with her, but turned back out of fear.

When authorities searched the home in Perris, 60 miles south-east of Los Angeles, investigators found some siblings shackled to furniture in the four-bedroom house.

Mr Hestrin said all 13 victims were severely malnourished and as a result some have cognitive impairment and a lack of basic knowledge. He said a 29-year-old female victim weighed just under six stone (37kg).

The victims were not allowed to shower more than once a year, he said.

Investigators also removed dozens of boxes, what appeared to be two safes and pieces of a bed frame during the searches.

In an interview, grandparents of the children said their son's family looked happy and healthy when they last visited California six years ago.

"They were just like any ordinary family," said Betty Turpin, the 81-year-old mother of David Turpin. "And they had such good relationships. I'm not just saying this stuff. These kids, we were amazed. They were 'sweetie' this and 'sweetie' that to each other."

Betty Turpin and her husband, James Turpin, of Princeton, West Virginia visited her son's family for five days at their previous home in Murrieta, California.

Betty Turpin told the Southern California News Group on Wednesday that they were still in shock from learning that her son and his wife were arrested.

Betty Turpin said her son told her he had so many kids because God wanted him to. She said her son shared her Pentecostal Christian faith but he wasn't affiliated with a church in California.

"I feel they were model Christians," she said. "It's hard to believe all of this. Over the years, the Lord knows what happened."

James Turpin said during their visit, "they all looked to me well-adjusted. They weren't skinny or nothing. They were joyous to see us".

He said they were dealing with social workers in attempting to connect with their grandchildren, who are hospitalised as they recover from their ordeal.

Police said they had never been called to the Turpins' home before and there were no reports fielded by child protective services.