Winter mentions that her grandfather died in an asylum, just like Scarlet's grandfather, Logan. Also, Cinder didnt know her father. Cress, however, isnt related by blood, but her father is Dr.Erland, one of Cinder's accomplices. Anyone agree or have simillar thoughts?
I disagree - Scarlet's grandfather, Logan Tanner, was a royal physician. Winter's father Evret was a guard and Solstice was a seamstress. I doubt either had much contact with the doctors, and their parents probably didn't either. Cinder's father is unknown, but he was a) either a peasant or b) someone who willingly went into the caves with Channary because she died of regolith poisoning. I am more likely to believe the latter. I think the main connection between them is that they are all Lunar, not that they are related.
On the other hand, I always was a fan of the conspiracy theory that Channary grew jealous of Evret and Levana and decided to take Evret as a sexual partner with her bioelectricity powers, sneaking off into the regolith caves for a romantic rendezvous. This would make Winter and Cinder half-sisters, and would also mean that Levana would not only be Cinder's aunt but also her evil stepmother... sadly it's probably not true :(
But, their common ancestor would have had to be really old when Cinder was born, and just my personal opinion, Channery Blackburn, queen of the Lunars, would probably want a young energetic, and handsome young man, but then again you never know if he was handsome, or if he lied about his age, because of like plastic surgery and stuff he could have looked younger than he was, but stll.