History of Oliverio

He was going to be a baby human; except that it was the product of a pregnancy unwanted by impatience and irresponsibility of a couple of young people who did not have any protection by having relations for almost 16 years ago, and Oliverio was sadly aborted by the couple when his is 9 weeks of pregnancy.
Although the doctors decided to keep the fetus and send it to a kind of laboratory to develop and see if any family would want to adopt it.
And yes! They sent it to a laboratory to perform the operation. However, that was a clandestine laboratory that towards experiments with material type extraterrestrial called Mutagen. Where the director and supervisor of all (by thus call it) was Erick Sacks.
Searching for your subject of tests for their next experiment: A hybrid mutant that you use as a deadly and dangerous weapon.
He had samples of DNA from many reptiles (among them the most dangerous and capable of camouflage and adhesion) even of prehistoric reptiles (dinosaurs that are considered dangerous).
Sacks thought using a common turtle as a base for experimentation but rejecting the idea. And suddenly found something else happens use as a base for the experiment: An aborted fetus.
Sacks and with the help of his scientists who found the way to use the mutagen in his experiments, created a serum with the following genetic components:

40% DNA from Turtle (Mostly for his appearance).
10% DNA from Alligator (For his ability to bite and the possession of his tail).
10% DNA from Komodo Dragon (Equally to bite too hard).
10% DNA from Gila Monster (To administer poison through his bite).
10% DNA from Gecko (For his ability to adhere in differents surfaces).
10% DNA from Chamaleon (To have the ability to camouflage and attack by surprise).
3% DNA from Velociraptor (To run like one, and the possession of a large and sharp nail in the toe of each foot.).
3% DNA from T-Rex (To be a predator like a King of 65 million years ago).
3% DNA from Mosasaurus (It serves to breathe under the water and attack if necessary).
Besides having the regenerative powers of some reptiles to replace any part of the body that falls off of he.
And 1% of what remains is human DNA, unfortunately this percentage is lost in his genetic code.

Oliver was going to be a deadly organic weapon, but he was kidnapped by the Kraang already was mutated by mutagen created by them.
But the KranngDroid carrying it, leave loose Oliverio by accident because he is moved eerily within the capsule in which he was.
Oliver fell down the drain and finish in the sewers where was found and adopted by Splinter and was trained along with his brothers; Leonardo, Donatello, Raphael and MichelAngelo.