I stumbled across a news story which will now be the default thing I bring up when the subject of astrology comes up. A scientific study found that students conceived between May and August had lower test scores than those conceived at other parts of the year. This is just on average. But it was across the board, regardless of things like race or gender or class. The theory proposed on why this might be the case is that during the months of May through August, that's when there's the highest concentration of pesticides found in ground water.