The black truffle of Périgord, the cynosure of every foodie’s dreams, is about to yield its most intimate secrets to a team of French and Italian researchers who have decoded its genome. Surely a great day for gastronomy and yet — truffle-lovers be advised — some of the new discoveries may reveal more than you really wanted to know.

Truffles are the fruit of fungi that infect the roots of certain trees. They are of keen interest to pigs, particularly sows, because some secrete androstenol, a hormone produced by boars before mating. People who use sows to hunt for truffles often find it hard to prevent a sex-crazed animal from eating the truffle she has found and may lose fingers in the attempt...