Astrology may usually be dismissed as a harmless superstition, but scientists are discovering that the date when we are born really can affect our later lives.

Research has shown that the time of year that people are born can influence their personality, their health, and even whether they are male or female. But rather than being written in the stars, studies are showing that it is the season of birth that predisposes individuals to different traits.

In the Northern Hemisphere, women born in May will display more impulsive behavior while those whose birthday falls in November will be more reflective. Men born in the spring will also show greater persistence than those born in winter.

Other research has indicated that people born in the autumn will tend to be physically active and excel in football while those born in the spring will be more cerebral and may be better suited to chess. Those born between September and December are more prone to panic attacks, while growing evidence suggests that the incidence of schizophrenia is higher among those born in the late winter and early spring.

“It is exactly what you would expect if it were temperature related,” a professor of psychology at the University of Hertfordshire, Richard Wiseman, said. Mr. Wiseman has examined the effect of the season of birth on whether people feel lucky. “Many of the effects reverse in the two hemispheres.”

A psychiatrist at Aberdeen University who has studied the links between season of birth and mental health, John Eagle, added: “The two main culprits … are diet and the seasonal fluctuations in nutrition, and the increase in infections during the winter.”

Astrologers have seized upon the findings as evidence that an individual’s personality is influenced by their star sign and justification for millions of people who pour over their horoscopes every day. But scientists insist that fundamental biological reasons underlie the effects, and not the position of the stars and movement of the planets. Jayanti Chotai at Umea University in Sweden said levels of hormones produced by a pregnant woman change depending on the season, and this could be “hardwiring” personality traits while a baby is in the womb. Temperature, infections, light exposure, lifestyle changes, and nutrition, which can all change depending on season, are all thought to influence these hormones.