Gwynevere
Geula Sinclair was the only child of Edward and Alicia Sinclair. That is, at least, what her birth certificate will reflect. Her mother having publicly kept a long-standing lover, Gwynevere will never know who her biological father was in this life. And, quite frankly, does not want to. Though she's considered having a parentage test several times, Edward was the one who raised her. Thus, Edward is the only father she will acknowledge, from now unto infinity.
Neither parent was particularly excellent. They loved her enough, but Edward was too depressed and absent-minded and Alicia was too blasé. Edward would attempt to bring Gwyn out to all sorts of activities, but he knew nothing about entertaining a daughter. (As a result, Gwyn has random 'manly' skills. Camping, rock-climbing, shooting, etc - yes.) Alicia did have her influence as well, teaching Gwyn to be the perfect hostess and house-runner. But Gwyn's relationship with her mother is rocky at best. Essentially, Gwyn's childhood is what you'd expect of a ridiculously well-off but dysfunctional family.
Gwyn was raised in the Church of England but converted to Catholicism as soon as she remembered who she was. She went to an all-girls private school, then Cambridge. She has no siblings. Her father's only sibling, a sister, died, leaving a cousin for Gwyn in Kendra Sinclair. (Hemera) On Alicia's side, she has no more than five cousins.