The TLC show My 40-Year-Old Child documents a rare and mysterious ailment that stunts development in children, leaving adults looking like kids.
Pam Brink, a mom from Marco Island, Fla., has a son who's 29, but has the body of a 10-year-old and the mental development of a child even younger:
Brink said her son Jeffrey was diagnosed after she noticed he wasn't aging the way he was supposed to and was suffering from severe handicaps.
"It was hard because there's a lot of challenges with taking care of a baby, which is what Jeffrey really is," she told the Huffington Post in an interview.
"He's probably between eight and 12 months as far as needing to be taken care of."
Mary Margret Williams from Billings, Mont., described a similar experience she went through in raising her daughter, 8-year-old Gabby Williams.
"We knew from really the get-go that Gabby had something wrong with her," she said.
"Right after she was born, she obviously wasn't sucking and wasn't doing all the things she should have done as a baby. ... She wasn't growing or changing."
Attending to the special needs of their children certainly present unique challenges.
All the families can do, they say, is work to look for the silver linings in their circumstances, and to give their children the love and attention they need.
"I just decided I'm going to love him and take care of him the best I can until I can't take care of him anymore," Brinks said of her son.
Take a look at more clips from the new series, which is getting a lot of buzz along with The Man With the 132-Lb Scrotum, below: