“People usually lie for one of just a very few reasons,” Dr. Phil tells 20-year-old Allie, who says she doesn’t know why she lies.

Three common reasons are:

1. Escape accountability.
   
   
2. Get access to things that they wouldn’t otherwise have.
   
   
3. Embellish reality.

“They think their life is boring and so they’re not getting payoffs. They’re not getting attention, affection, sympathy, praise,” Dr. Phil says. “So they enhance their reality, hoping that they’ll get something that they weren’t getting.”

Dr. Phil continues, “Before you know it, one lie leads to another, and then another and then another.”

Allie’s parents claim her lies, which started small like lying about doing her homework, have grown to larger fabrications like pretending to be pregnant, having a miscarriage and having a baby that died. They claim her lies are ruining their lives and have cost them relationships with family and friends, their business, more than $100,000 in legal fees and have landed them both behind bars. Watch their story here.

This episode of Dr. Phil, “Facing Jail Time Because Stepdaughter is a Liar,” airs Monday. Watch more here.