“Most people, even most doctors, learn that the placenta is a nice, tight seal that prevents anything in the mother's body from invading the fetus, and vice-versa. That's mostly true. But the placenta doesn't seal off the baby perfectly, and every so often, something slips across.”

American writer

Sam Kean is an American writer known for books that tell the story of scientific discoveries in a narrative style. He was born in Sioux Falls, South Dakota, and lives in Washington, D.C. He has written for The New York Times Magazine, Mental Floss, Slate, Psychology Today, and The New Scientist. He has also published eight books, and they have been reviewed positively by The Wall Street Journal, Library Journal, and The New York Times.