Great Great Grandmother Pearson is the wife of Skip, ex-wife of The Woodsman, mother of Great Grandfather Pearson, and Great Great Grandmother of Chris Pearson.
She apparently married The Woodsman sometime prior to his disappearance, as they had recently conceived a child. After three years, she was legally forced to remarry, and choose Skip, a wealthy British man. She forced her former husband to sleep in the barn, leading to his mental breakdown. She fled to America in response.
Despite her accent, the genetic evidence suggests she is not, in fact, Canadian. Assuming none of the woman her children met in America were Canadians, Chris is 1/16th Canadian, making his father 1/8th, his grandfather 1/4, and her son 1/2. As The Woodsman is a pure Canadian, this suggests she was not, and instead likely hailed from The British Isles.