The Biology of . . . Sex Ratios

Some couples worry—a lot—about whether they will have a boy or a girl. So they try any number of strategies to influence nature’s choice. Folklore says eating more red meat increases the chance of having a boy. So does having sex standing up or during the quarter moon or on odd-numbered dates. A diet of fish and vegetables, on the other hand, is said to produce girls—as does having sex when the moon is full or the date is even. Some popular books say having sex during ovulation is likely to produce a girl, others that it more often leads to a boy.