More often they offer benedictions over the living. “There is something wild-eyed about whiteness right now, at this moment in history,” Imani Perry writes in “Breathe,” a letter to her sons. Many of these memoirs crystallize around the killings of black men and women, of Renisha McBride, Trayvon Martin, Tamir Rice, Eric Garner. “I write you in your 15th year,” Coates addresses his son at the beginning of “Between the World and Me.” “This was the week you learned that the killers of Michael Brown would go free.” In the opening scenes of “Breathe,” we find Perry and her son sitting on the sofa, listening to the news of Troy Davis’s execution. These memoirs are full of the love and frantic fear black parents feel for their children, and the fugitive hope that education or class might offer some measure of protection. But they are also rich evocations of abundance: “I cannot clip your wings,” Perry writes to her sons. She will not permit them lives of narrow circumspection: “I want your wingspan wide.” Several accounts vibrate with the exhilaration and anxiety of rupturing ancient silences. “I was the third generation of things we didn’t talk about,” Terese Marie Mailhot writes in “Heart Berries,” a series of letters to her lover, in which she delves into her childhood on the Seabird Indian Reservation in the Pacific Northwest, and familial legacies of abuse and addiction. In “Heavy,” an exorcism of his childhood in Mississippi, Kiese Laymon addresses his beloved mother: “Neither of us would ever, under any circumstance, be honest about yesterday. This is how we are taught to love in America,” he writes, remembering the brutal beatings she administered in an effort to make him so perfect, so unimpeachable, that he might survive America.

It’s a recurring note in several books — a parent’s cruel and desperate attempts to toughen up a child for the world. “I grew up in a house drawn between love and fear,” Coates writes. “I would hear it in Dad’s voice — ‘Either I can beat him, or the police.’ Maybe that saved me. Maybe it didn’t.” In Ocean Vuong’s essays and autofiction written as letters to his mother (a Vietnamese immigrant), he imagines something similar: “Perhaps to lay hands on your child is to prepare him for war, to say that to possess a heartbeat is not as simple as the heart’s task of saying yes yes yes to the body. I don’t know.”

Those notes of uncertainty interest me — “Maybe that saved me. Maybe it didn’t”; “I don’t know” — given the form’s history. Traditionally, the memoir addressed to one’s descendants enshrined an official family story. “Dear Son: I have ever had pleasure in obtaining any little anecdotes of my ancestors,” Ben Franklin begins his “Autobiography.” “Imagining it may be equally agreeable to you to know the circumstances of my life, many of which you are yet unacquainted with, and expecting the enjoyment of a week’s uninterrupted leisure in my present country retirement, I sit down to write them for you.” The memoir continues in this vein of purring complacency, the sweetness of a life tasted twice, first in the living, then in the telling.