The next several pages are intended as a "Commentary" on the six target articles bundled together as a Special Issue of the "Journal of Cognition and Development"--literature reviews and research reports all intended to "build bridges" between the study of cognitive development in typical and atypical populations.

Genetic and epigenetic differences exist within monozygote twin-pairs and might be especially important in the expression of autism. Assuming phenotypic differences between monozygotic twins are due to environmental influences may lead to mistaken conclusions regarding the relative genetic and environmental contribution to autism risk.

A recent large-scale meta-analysis of twin and adoption studies indicated that shared environmental influences make important contributions to most forms of child and adolescent psychopathology (Burt, 2009b). The sole exception to this robust pattern of results was observed for attention-deficit/hyperactivity disorder (ADHD), which appeared to be…

In February of 2000, "Exceptional Parent" introduced readers to the Crowley family. The author profiled John, Aileen, and their three children: Megan, Patrick, and John Jr. They told "Exceptional Parent" that in 1998 both Megan and Patrick were diagnosed with Pompe disease, a progressive, multisystemic, debilitating, and often fatal muscular…

According to the medical profession the direction and scope of reproductive services such as IVF and pre-natal screening are based on solid evidence; the evidence indicates these are effective and safe services. Moreover, women want them. As a consequence these services are usually presented to the wider community in a positive light with images…