Correct, but the number of female mortals around at the time of Bob’s conception and introduced as a character we have met in the Dresden Files is zero.
We have also not been introduced to a Male muse or equivalent like Lea. Theoretically it could be one of the ‘male’ Denarians and I have posited Namshiel/Marcone somewhat as producing a new spirt of intellect explaining vanilla Marcone able to do magic in jest BUT Bob has problems with Angelic energy as not being on his wavelength suggesting Bob doesn’t have a Denarian or angelic parent, unlike Bonea.