Making Babies

Forty years ago, there was exactly one way for humans to reproduce. A man’s sperm would combine with a woman’s egg, inside of her body. Together they would form a zygote, which would become an embryo, and then a fetus. With any luck, the woman would carry the fetus to term, and a baby would be born. The process had not changed since long before anyone could call us human. Until one day, after years of trial and error, Dr. Patrick Steptoe and Dr. Robert Edwards combined an egg from Lesley Brown with sperm from her husband, John, in a petri dish and implanted the resulting embryo in her uterus. On July 25, 1978, Louise Brown came squalling into the world, heralding a revolution not just in the mechanics of reproduction but in the surrounding culture.

At the time, James Watson, a co-discoverer of DNA’s double-helix structure, warned that if in vitro fertilization were allowed to proceed on a broader scale, “all hell will break loose, politically and morally, all over the world.” Since then, not only has reproductive technology gone ahead...