Former Poland and Lens striker Joachim Marx coached Kakuta at the French centre of excellence in the northern city of Lievin. Now a scout for Lens, Marx, 65, offers a fascinating insight into his protege's early career.
"The easiest way to describe him is a phenomenon," said former Lens boss Marx.
"I was director of a French Federation football school when I first worked with him. Between the ages of 13-15 you could see he had everything.
"Perhaps one criticism was that he didn't try very hard sometimes in training - because he didn't need to! He could already do everything."
It was a talent that did not escape Chelsea's Frank Arnesen, and, as Marx revealed, the interest from Stamford Bridge had a dramatic effect on Kakuta's career path.
"His mum wanted him to stay at Lens because they had a good plan mapped out for him, which included getting an education and working at his football before eventually progressing to the first team," Marx told the Daily Mail.
"But Gael didn't want to go to school. He was at that age when he only wanted to be a footballer. He actually ended up having to repeat a school year because he didn't pass his exams.
"Lens had an agreement signed with him. Chelsea are a rich and powerful club and Gael's mum changed her mind for whatever reason. In my opinion he was too young to leave and go to Chelsea. We told him he had lots of time to move later on but he was seduced by Chelsea."