Human abilities and disabilities are a product of the interaction of biology and experience. Though this seems obvious, the debate over nature and nurture has lingered for decades, and there are still those who adhere more to one camp than the other. In this essay the focus will be on the genetic aspects of development; but, it should be acknowledged at the outset that both genes and environment are important to some degree in the development of language skills, be they normal or abnormal (Gilger, 1995; Pinker, 1994; Snow, 1996). Essentially, there are no exceptions to this rule, even as it applies to the language disabilities in well defined populations with a genetic anomaly (e.g., the symptoms of individuals with Trisomy 21, Fragile X, Velo-Cardio-Facial Syndrome, and others, depend on the action of genetic as well as nongenetic factors; Gilger, 1995; Rimoin, Connor, Pyeritz, 1996).