Ah, and here we are. I just knew this would come up eventually.
What you must understand is, as a vampire your relationships to others are not so clean-cut as they might have once been as a mortal. There are nuances and subtleties that exist beyond the human scope. You stop seeing things as being taboo or immoral. You simply love a being for what they have to offer you.
Yes, Gabrielle is my biological mother, but when I turned her she became something else to me as well. She was less of a caregiver and more of a companion. I can see how you might misconstrue our relationship as potentially awkward if you are thinking of us as a mortal mother and son. Yes, that would indeed be strange. But that is not the case let me assure you.
And no part of our relationship affects me day-to-day. This is mostly because I see her only every several decades.