His mum, Victoria Holt, 30, says that no one in their family looks the same as Chase and that even strangers assume he's a little girl due to his hair type and facial features.
Chase's parents are of Jamaican and Asian heritage with no direct relatives having blonde hair.
Victoria, a mum-of-four, said: "We honestly have no idea where his blonde hair and fair complexion has come from. It's a complete mystery."
"I'd really love to do one of those genealogy tests to see if we can track where his blonde hair came from."
Chase has three other siblings; Kyla, seven, Tyrese, five, and Romeo, five months, and all of whom look extremely different to their four-year-old brother.
Chase is part of a modelling agency along with his sister Kyla, but Victoria has found they haven't been put forward to any sibling modelling opportunities since they look so different.
The mum of four said: "I would love for the two of them to be in a shoot together but it's quite likely directors would choose other siblings over them."
"They just look so different - the only thing that connects them together is their curly hair really."
"Kyla adores Chase's hair and is always playing with it."
"She's really big on Barbie dolls, which obviously have blonde hair, so she often says she wishes she had blonde hair like her little brother."
Due to the physical differences in the siblings, Victoria worries people may think that Chase isn't her child.
She added: "When I'm out and about with all four of them, I genuinely worry people look over and think Chase isn't mine or that he might have a different dad to his siblings."
"His aunties always chuckle about how luckily Chase looks exactly like his dad when he was a kid but just a white, blonde version."
"It's crazy to think his hair changed so drastically over such a short period of time."
"When he was one, we'd just moved house and the he played in the garden all summer, which is initially why I thought his dark hair went so light. But when winter came round, his hair was still a blonde as before."
"I was baffled then about it as I am now."