Grace and William [absolute spoilers]

[Marlon]

How did William really die?

Because throughout the course of the book, when Grace gets frustrated, she hears a buzzing in her head that makes her lose control. I morbidly suspect that William may have cried too much, causing Grace's head to buzz, and she just tried to do deal with him in an uncontrolled way like shaking him. Which would sadden me because Grace has such innate maternal instincts, at least that much she shown with her time with Joceylyn.

[Lynda]

William died of SIDS which can claim a seemingly healthy baby up to one year old. It's tragic for any family and sadly our society can't accept that no one was at fault. All too often, they point a finger at the mother, even if there are no charges laid, and the stigma lingers. It's the old "where there's smoke there's fire" way of thinking.

[Marlon]

Ah I knew my speculation was inconsistent with her character. Thanks for the clarification! I didn't know such a thing as SIDS existed, that is tragic as all hell.