More on Birth Seasonality and Schizophrenia

To the Editor.—  Dr Watson and colleagues¹ reported findings relating birth seasonality in schizophrenia to years with high rates of pneumonia, influenza, and diphtheria in the winter prior to birth. These are fascinating results, even if they are counterintuitive. If they are replicated, perhaps the effects of infection prior to conception could be explained by a recent suggestion by Crow.² He posited the incorporation of a retrovirus into the genome at a site close to a hypothetical gene for cerebral dominance. While this viral integration could occur during pregnancy in the fetus, he cited studies suggesting that retroviruses may infect the germline in a parent, and that this may account for the fact that they may be transmitted to at least the next generation.Published at almost the same time, Crow's² hypothesis and the data of Watson et al¹ are consistent with each other. While there