Since according to the PHB,
"Sorcerers carry a magical birthright conferred upon them by an exotic bloodline, some otherworldly influence, or exposure to unknown cosmic forces. One cannot study sorcery as one learns a language, any more than one can learn to live a legendary life.
No one chooses sorcery; the power chooses the sorcerer. Magic is a part of every sorcerer, suffusing body, mind, and spirit with a latent power that waits to be tapped. Some sorcerers wield magic that springs from an ancient bloodline infused with the magic of dragons. Others carry a raw, uncontrolled magic within them, a chaotic storm that manifests in unexpected ways.
The appearance of sorcerous powers is wildly unpredictable. Some draconic bloodlines produce exactly one sorcerer in every generation, but in other lines of descent every individual is a sorcerer. Most of the time, the talents of sorcery appear as apparent flukes. Some sorcerers cannot name the origin of their power, while others trace it to strange events in their own lives. The touch of a demon, the blessing of a dryad at a baby’s birth, or a taste of the water from a mysterious spring might spark the gift of sorcery. So too might the gift of a deity of magic, exposure to the elemental forces of the Inner Planes or the maddening chaos of Limbo, or a glimpse into the inner workings of reality."
I think it is more individual than race. The member of a D&D race has an entire culture surrounding him with all its expectations, helps, hinderances and lore; even if a sorcerer's power is not a freak influence from beyond, yet his bloodline is a very personal or at most familial thing. Much like Vampirism in Vampire the Masquerade.