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.

These are interesting days in the scientific, social, and political debates about human embryonic stem cell research. Pluripotent stem cells--cells that can, in principle, give rise to the body's full range of cell types--were previously derivable only from human embryos that were destroyed in the process. Now, a variety of somatic cell types can…

The connection that critics make between medical genetics and eugenics is historically fallacious. Activists on the political right are as mistaken as activists on the political left: Genetic screening was not eugenics in the past, is not eugenics in the present, and, unless its technological systems become radically transformed, will not be…

Government regulation of recombinant DNA research is addressed. Issues discussed include the potential of such research; National Institutes of Health guidelines; federal, state, and local regulation; the controversy over self-regulation; first amendment protection for scientific research; and problems in drafting legislation. (JMD)