The simultaneous existence of two separate sets of circumstances does not prove a correlation, so we should want to see a lot more evidence before we accept this possible link:
Does the time of year in which a child is conceived influence future academic achievement? Yes, according to research by neonatologist Paul Winchester, M.D., Indiana University School of Medicine professor of clinical pediatrics. Dr. Winchester, who studied 1,667,391 Indiana students, presents his finding on May 7 at the Pediatric Academic Societies' annual meeting.
Dr. Winchester and colleagues linked the scores of the students in grades 3 through 10 who took the Indiana Statewide Testing for Educational Progress (ISTEP) examination with the month in which each student had been conceived. The researchers found that ISTEP scores for math and language were distinctly seasonal with the lowest scores received by children who had been conceived in June through August.
Why might children conceived in June through August have the lowest ISTEP scores? "The fetal brain begins developing soon after conception. The pesticides we use to control pests in fields and our homes and the nitrates we use to fertilize crops and even our lawns are at their highest level in the summer," said Dr. Winchester, who also directs Newborn Intensive Care Services at St. Francis Hospital in Indianapolis.
On the other hand, I was born in September, which means I was conceived in December. Maybe I should just accept the theory, since it would explain why I'm so much smarter than so many of you.