How they all came to be.
The series of Guardian Genesis is a collection of stories that is based off of real life players but set in the world of Destiny. Each person is asked their favorite race, class, subclass, planet, and enemy. The final question is whether they want the story set during the Golden Age, The Collapse, or during the current Destiny timeline. Each story is either earned by getting a specific trophy in the clan of xAllegiancex or is gifted by Isakole.
With so many Guardians running around at the Tower why wouldn’t each one have their own story of how they came about? Each one is as unique as the player, the personality of the Guardian just like the person at the controller