The secrets that motivates the actions of her parents are not known by Grace. This is where this novel sings. Grace is a full bodied character. Easily identifiable with the way she felt about herself, her family. A definite plus.
Grace is a lesbian.
Her sexuality isn't spotlighted to the point that it is her main purpose in life. It's a part of Grace, the same as her skin color, or the fact that her mother's name is Camille. But it is examined. For this is one of the essential components that is Grace. Don't preach, tell a story.