Tens of thousands of years ago, a mysterious race of intelligent robotic alien creatures established an outpost station on the Jovian moon of Ganymede, where they soon discovered the neighbouring planet Earth, and by extent, the primitive human life. Upon arrival, they would experiment on certain specimens and their DNA in the hopes of learning about their species and biology, as well as to use as weapons.
While the result was successful, the newly-created hybrids would soon revolt against their makers and masters, and went on to form a society of their own, which thrived and absolutely secluded itself far from the rest of humanity and developed advanced technology. Exposure to a mutagenic substance known as 'Cybergen' (which was a major element used by the creators to make their creation) would give them the power to transform into any shape or form at will, but would also cause significant genetic damages and deformities. This led to a long-term selective breeding program in an attempt to reduce such mutations.
However, while most of them live in their isolated city of Henshin, currently located in Mars, some specimens remained on Earth and mated with the rest of mankind, passing down their genes (soon to be dubbed 'Gene-6').
But regardless of wherever they may be, they would all eventually be known as the TransHumans...