When the Kaminoans first created the Alpha Batch, they used pure DNA from Jango Fett, a man who claimed to have less Taung in his DNA then he let on. The Alpha Class had turned out horribly- they were aggressive, often fighting amongst rank, hard to control, and far to independent to make good soldiers. so the long necks tried again, creating the Commander Class or CC clones. They had only used half of Jango's DNA this time, and yet- the Commanders had turned out aggressive, though not often fighting, difficult but not impossible to control and still independent, so the Kaminoans had tried one last time. They created the CT's, the most far removed from Jango Fett clone troopers ever. they took orders well, and where just the right amount of tactical to be able to run a battalion. the problem was, one CT was created with a mutation- a single mutation that ran in their DNA.