Could Joe be the world's youngest transgender?

The boy's parents, Matt and Rosie Downes, said they noticed the difference between Joe and his twin brother Olly from a very early stage.

"My earliest memory of it is at one and a half. My parents had them once a week from when they were born. Mum and dad used to take them down to the shops to pick a magazine. Olly would get Thomas The Tank Engine, or more "boy" magazines. She picked something pink with fairies. From the age of two she was drawn towards pink toys and babies. She asked for baby dolls and wanted girly fancy dress while Olly had a Batman outfit," Matt told Daily Mail.

"It really hit at three when she went to preschool. In the first three weeks, we asked the teacher how they were settling in. She said Olly has been outside playing in the sandpit, playing with the boys. 'While Lily has been in the fancy dress all day. She was drawn towards girls and built bonds and friendships with them," he added.

Downes said as parents they thought they may be fueling the situation as Joe was still very young, but it really hit them hard when he came up with a new name for himself, Lilly, and was vocal about his desire to be a girl.

"We had a bit of resistance when Lily was three, we were concerned we were fueling situation and she was too young to understand. That Christmas, we bought more stereotypically "boy" toys for her but we ended up taking them back because she didn't want them. Lily refused to wear anything other than girl's clothing and was vocal about her desire to be a girl," Matt said to the publication.

Joe is reportedly now wearing school uniform for girls and society has accepted her as a girl.

Speaking to Victoria Derbyshire of BBC News, Lily said" “'If I had to live as a boy I'd be really upset”.

Watch the interview below: