“Older siblings get more total-immersion mentoring with their parents before younger siblings come along. As a result, they get an IQ and linguistic advantage because they are the exclusive focus of their parents' attention.”

American magazine editor and author

Jeffrey Kluger is an American magazine editor and author. He is editor at large at Time magazine and has written thirteen books across a range of subjects. His books include works on psychology, medicine, family dynamics, and spaceflight, among them The Narcissist Next Door, Splendid Solution: Jonas Salk and the Conquest of Polio, The Sibling Effect, and Lost Moon: The Perilous Voyage of Apollo 13. Lost Moon later served as the basis for Ron Howard's film Apollo 13. He has also written two young adult novels and one novel for adults, Holdout.