The Yoshi DNA was discovered on the destroyed Yoshi's Island, after the Super Happy Tree drained it of it's resources. After being found by a a turtle, the turtle mysteriously died. Some people claim this to be the work of Nintendo, except it has never been proven. It was then said to be taken to one of Nintendo's special labs, where it was born.
There have been many rumors about the creation of Yoshi. Some say that it was the child of two other Yoshis that died. Others say that it was a mutated dragon, which at that time roamed the skies after defeating the English Muffins. Only one thing can be sure, it was brought back to life at one of Nintendo's labs. At first, the Yoshi seemed to be friendly with everyone. But soon, it becamed angry, probably due to the fact that they fed it table scraps. They underestimated it's intelligence. Soon, it was time for him to strike...
One day, during a test in which Yoshi had to explain Einstein's theory of cheese, Yoshi broke out. He ran through the streets of Spain, eating everything in it's path. It was then found out it could reproduce without the help of another Yoshi. All it had to do was swallow an object, and a new life was born. These Yoshi's came out different colors then their parent. This was thought to be the work of the Radioactive Bulls, the leading gang in Purple Dove. It was found out later that even the males could reproduce! All this reproducing caused conflict between the United Nations. They could not have children watching this! And so, a plan was hatched(No pun intended).
They had to lure Yoshi back to it's island. To do that, they replanted the Super Happy Tree. The plan was successful! But they decided they could not let this creature live. They bombed the island, and so, Yoshi was dead.
In the 1990's, Yoshi was reborn by Nintendo. This time, to make sure it didnt get out of hand, they forced it to carry Mario over and over again. Yoshi didnt mind this, although there are a few that say that Yoshi looks sad in his pictures. Another factor leading up to its reborn was cults devoted to it. They sacrificed bananas and watched Yoshi pornography to please it. And soon, their prayers were answered. Today, Yoshi lives in a mansion on one of the islands that had taken over the UK.