The Channel 4 documentary, which aired on 6 October, followed two seven-year-old children, who now identify as a different gender to the one they were assigned at birth.
One of those children was Paddy McGuire from Leicester.
When Paddy was born, she was labelled as a boy, but Paddy's father says that from the age of two she "showed interest in being a girl".
The show saw Paddy asking her dad to paint her nails and dancing in a sparkly dress, looking very happy at home.
She exclaimed: "I don’t want to be a girl. I am a girl."
Mum Lorna said the only wish she has for her daughter is for her to be accepted for who she is.
But it was Paddy's dad, Paddy senior, who caught the hearts of the viewers.
"These are normal children," Paddy senior said on the show.
"They're not some circus freaks. They're normal children who were born with the wrong plumbing."
Many viewers were so touched by the dad's words that they took to Twitter to air their views:
Isn't Paddy's daddy a lovely man. Taking that in his stride is really remarkable #mytransgenderkid— Anne Marie O'Connor (@Kitsgirl1) October 6, 2015
Watched #MyTransgenderKid last night. What wonderful parents, especially Paddy's Dad.— alexa milne (@Alexa_Milne) October 7, 2015
Emotional watching #MyTransgenderKid. Cheering to see parents accepting & loving them as they are. Paddy's dad doing her nails? *blub*— Stewart Who? (@DJstewartwho) October 6, 2015
Paddy's dad seems like the sweetest man on #mytransgenderkid love this programe❤️— Lauren (@lareeves22) October 6, 2015
Paddy's dad is truly an inspiration to everyone. What a guy. #MyTransgenderKid— Bobo Balti (@bobobalti) October 6, 2015
Paddy's parents are outstanding. Such a beautiful family with a headstrong child who is so sensible with her decisions! #MyTransgenderKid— Matthew Brazier (@_matthewbrazier) October 6, 2015