Hey there!
I'm also a descendant of George and Susannah, by the looks of my research, and what I've seen is that George was NOT the son of Christopher Martin.
The information I've found says that Christopher and his wife, Mary, only had one son named Nathaniel, and she had a son named Solomon from a previous marriage, who came with them on the Mayflower.
As of writing this, I haven't found any information on who George Martin's actual parents are.
Regards,
Kaleigh A. Mitchell