Neuropsychological Performance in the Unaffected Twin-Reply
Abstract
Abstract In Reply.— As Dr Green implies, the interpretation of the comparison of unaffected and normal monozygotic twins is complex and open to a number of interpretations. We have examined the issue in more detail in an unpublished manuscript. To summarize our conclusion, it appears that the emotional burden of having an ill cotwin, differences in cooperation and anxiety level, and small differences in parental socioeconomic status might have contributed to the effect sizes that we...