The English biographer Claire Tomalin’s memoir, “A Life of My Own,” is on one level a phlegmatic tour of a fruitful life. She guides us briskly through her childhood (her French father worked for Unesco; her English mother was a musician), her education at Cambridge University a year ahead of Sylvia Plath, her early marriage and four children, her years in London’s literary world as the editor of book review sections, and finally her emergence, starting in her 40s and 50s, as the esteemed biographer of Samuel Pepys, Jane Austen, Charles Dickens and others.

On another level, the book is one shock after another. Tomalin was a second child, born in 1933, and “as soon as I was aware of anything,” she writes, “I knew my father disliked me.” His name was Émile Delavenay, and his hostility toward her was inexplicable until much later. That’s when she read, in his own memoir, that shortly before she was conceived he had considered killing her mother by pushing her from a high cliff.

Tomalin’s parents divorced, a scandal in the 1940s. Her mother was so distraught she threatened to put her head into a gas oven when her daughters left to visit their father in the United States. The author found consolation in reading. “My mother told me early that whatever happens to you, however unhappy you may be, you can escape into a book.” Here, too, events conspired against her. When young she read a book called “Tom Brown’s School-Days” and — well, let’s let her tell it:

“I had been reading ‘Tom Brown’s School-Days’ and learned there that, if you simply threw yourself into some deep water, you would find yourself swimming automatically. Trustingly, I put on my bathing suit and leaped into the pool. I have a clear memory of sinking through the water, beginning to choke.”

She might have died had not a quick-witted observer plucked her out. (Books, as Philip Larkin explained in his poem “A Study of Reading Habits,” are a load of crap.) Tomalin got a further shock in her school days when an adult explained to her that sex “was just like going to the lavatory.” She is compelled to add, for the disbelieving, that “those were his exact words.”