Sorcerers are born with power. Everybody knows that.
The exact KIND of power, on the other hand, is a more complex issue. There are nine sorcerous bloodlines detailed below. These bloodlines, as presented, describe in detail everything you need to play a Sorcerer character. That being said, these Bloodlines are not tightly defined as to the exact source of the power. They are (very deliberately) left 'open ended'. The exact concept of your character is, as always, up to you, the player.
We encourage all players and referees to explore the backstory and history of each Sorcerer in detail. Having the Boreal bloodline is all well and good, but is this due to your Grandfather marrying a Sylph Queen, or an ancestor that immigrated from the Plane of Air, or a transfusion to your great-grandmother of Air Elemental Essence to cure a childhood ailment, or your family has been Sky Cultists for generations, or you're one-sixteenth Djinn, or, or, or....
The exact details can be (AND SHOULD BE!) as widely varied and fanciful as you want. We encourage you to let your imagination run free, working with the Game Master, to create a fun, interesting character that you like to play. But always remember, the more details you put in, the more 'real' your character will feel, but if you don't want to bother with all those details, you may simply play the material as presented.
The choice is up to you!
Your ancestors have always shown an affinity for the most esoteric expressions of magic.
Your ancestors are a freedom-loving, wind-blown lot.
Your ancestors were erudite, highly cultured, and some would even say, otherworldly.
Your ancestors were important in the Workings of Deities.
Your ancestors were Big Players in the fate of the Natural World.
Your ancestors have gifted you a deep connection to the physical world through your aura.
Your ancestors forged a long and fruitful relationship with the Universal Fire.
Your ancestors were adherents of The Primal Storm, that raging, unending maelstrom.
Your ancestors have had dealings with... Things best left alone.