Rich and Jade are children of a spy.
They are not spies themselves nor do they have aspirations to become ones. They are teenagers and that is pretty much what they want to be. They are twins which means they are quite used to being with eacy other. They are definitely individuals with each having his or her own likes and dislikes and desires and phobias but having spent so much time together, they can usually know what the other is thinking just by feel.
The reason they had no desire or inclination to be an agent like their father is because until their mother died accidentally crossing a street (just moving back to Manchester from many, many years in New York, she made a common error and looked the wrong way first before stepping off a curb) they had no idea who their father was. They knew, of course, that they had one and that his last name was Chance but that was the sum of what they knew about him. They were not even sure if their mother knew or liked or loved the man who would help create them. They knew only that he had never for a moment been a part of their existance from the time they were born to the time at their mother's funeral they were introduced to each other.
The unfamiliarity went both ways. John Chance had known their mother and had loved her a great deal but for reasons he did not feel right to divulge, she had walked out on him and went to America. It was over and he regretfully moved on. The fact that she was pregnant was something neither knew then. When she learned it, she opted to go it alone. She had a good job working for a multinational computer company. She was smart and independent and self-reliant. That is how she raised her children to be as well.
Rich and Jade are 15 when the series begins. They had recently moved back to England with their mother before her death and afterwards had stayed temporarily with her friend and her husband who had no interest in brats taking up his space. Things went even darker when they met their biological father and realized that since he did not know of them before the lawyer contacted him, he was almost as unhappy about their presence.
To be fair to John Chance, his wanting or not wanting children was a moot point but worse at the time was the fact that he was in the middle of a very dangerous operation, one that could get himself killed very easily but with the arrival of the twins, not only were their lives in danger, there were suddenly two items the bad guys could hold over him.
Rich and Jade may not have wanted to be spies but when their newly found father gets into trouble, they find themselves forced into service. Training might have been nice.