US man Lee Kaplan has been arrested and charged after 12 Amish girls were found in his home. Picture: Lower Southampton Police Department via AP.

51-year-old Lee Kaplan was arrested on Thursday afternoon after police received a complaint about the health and welfare of numerous children living on his property.

Of the 12 girls, it’s alleged that Kaplan considered the 18-year-old teenager as his wife, and had fathered two children with her. Police said that one of the children that he allegedly fathered is 3-years-old, and the other is an infant.

Authorities say the teenage girl admitted to having sex with Kaplan when she was 14, and that she was not married to the man.

CBS Philly reports police believe all of the children are originally from an Amish community in Lancaster County. It’s understood that the 18-year-old, who Kaplan claimed to be his wife, was gifted to the man by the girls parents.

According to documents, the girl’s father told an officer he gave his daughter to Kaplan after he helped the family out financially.

Officials say the teen’s father, 43-year-old Daniel Stoltzfus, said he and his wife Savilla did it after “researching the legality of it on the internet”.

Police say the teenager’s father knew she was 14 when she first became pregnant.

Lee Kaplan has been arrested after police found 12 girls in his house, with one teenager allegedly fathering two of his children.Source:AP

The other 11 girls who were found in the small home were aged between 6-months to 18-years old. Police say it is unknown if any of these other children were subject to any abuse.

Authorities have not uncovered birth certificates for any of the girls, and have been unable to find any information about them.

“We believe that they’re originally from Lancaster County in the Amish community,” said Lower Southampton Township Police Lt. Ted Krimmel.

“Right now we’re working on getting an expert on Amish culture to help us conduct interviews on the rest of these children.”

One of the neighbours who contacted authorities said she did so after seeing multiple girls wearing blue dresses who looked unhappy.

“I just wasn’t gonna let go. I saw a couple girls last week standing in the driveway. They just looked unhappy and sad and again in the blue dresses, and I’ve been telling my husband for years something isn’t right, something isn’t right,” the neighbour told ABC news.

The parents of the 18-year-old and Kaplan are all being held for US$1 million bail. Mr Kaplan has been charged with sexual assault, aggravated indecent assault, indecent assault, corruption of minors and unlawful contact with a minor.