The ancestral bloodline, as I stated in my previous post, is in my opinion, a very common theme whether abyssal, dragon, infernal, fey, homo magus (or its equivalent in a given setting such as Halliwell lineage (Charmed), Dragonlord lineage (Scy Fy's Merlin).
The new powers and abilities in 3e could be
1. Heritage Manifestation, but this was a supplemental option and not hard wired. I like this as an option, but prefer the metamagic sorcerer house rule that appeared on message board early in 3e in which sorcerer's didn't need simple components and could innately shape magic.
2. Learn new spells. One can view the acquisition of spells as simply a new manifested ability, but it could also be an acquired learned ability (I assumed self taught through trial and error/experimentation). There was also a variant in the DMG that required the sorcerer to find a trainer to teach them a new spell. I prefer the learned approach whether through self teaching or having someone else teach.