|This article centers around Kenneth DiLaurentis, a book character. For another version check out Kenneth DiLaurentis, a TV character.|
Kenneth DiLaurentis is Jason's father and Alison and Courtney's legal father.
His wife, Jessica, cheated on him with Peter Hastings and together, they had twin daughters, Alison and Courtney.
Kenneth DiLaurentis and his wife, Jessica, attended the same law school, Yale Law School, as Veronica and Peter Hastings. Jessica had an affair with Peter around the same time he and Veronica had tried to conceive Spencer. At the time the twins were conceived, it is presumed that Veronica's surrogate, Olivia Caldwell, was already pregnant with Spencer since she was born around two months before Ali and Courtney.
The DiLaurentises originally lived in Connecticut until the girls were about 7–8 years old. Courtney had forced Ali underneath the water of their swimming pool and their parents were horrified by the fact that they had a mentally unstable child. They eventually moved to Rosewood, where Courtney was quickly placed into the Radley, a mental institute, and the family pretended there were only two children. It is unknown why exactly Rosewood was chosen as the desired place to reside, but it certainly wasn't a coincidence that the DiLaurentises ended up living on the same street as the Hastings family and as next-door neighbors. On the night of "Ali's" disappearance, his wife, Jessica and Peter were together on Spencer's porch. Presumably, they resumed their affair sometime after she and her family got settled in.
When the Radley was closed, Jessica and Kenneth had to send Courtney to a new institute. They chose the Preserve at Addison-Stevens, a lush clinic located near the border between Pennsylvania and Delaware. Courtney was extremely upset and didn't want to go. She managed to successfully fool her mother into taking her sister to the institute instead. It is rather odd that Jessica didn't notice anything amiss: though the twins were supposedly "identical", there were some subtle differences in their faces (Ali had a slightly thinner face, Courtney's was more heart-shaped) that any parent should have recognized. Regardless, she took the wrong daughter to the institute, unwittingly changing the lives of the entire family forever.
In Ali's Pretty Little Liars, it's revealed that the family knew from the get go that one daughter killed the other, but they didn't realize the girls were switched.
It is hinted that Kenneth knew the truth about his daughters' paternity and fought constantly with Jessica. The real Alison noted that she was surprised they had not gotten a divorce yet. It is uncertain if Courtney or Jason knew, though the latter most likely came to his own conclusions on the matter.