Since by now it is well documented that there are differences in the ways grown men and women speak, it seems reasonable at this point to ask where those differences originate. There are, of course, a number of plausible explanations of the origins of sex differences in language: They can arise either from inborn differences or as a result of environmental forces, or perhaps as a result of an interaction between the two. In this chapter, the emphasis will be on environmental forces, especially the role mothers and fathers play in shaping the language of their daughters and sons. This is not an attempt, however, to say that there are no inborn differences. The work of McKeever (Chapter 10 of this volume), Witelson and Pallie (1973), and many others has shown that it is entirely likely that the language areas of the brains of males and females are not identical: Specialization for language appears to develop earlier in the brains of females, and males appear to be more vulnerable to every kind of insult that affects language development and retention at every age from early childhood through advanced old age.

Even if there were no differences in the neuroanatomical bases of language in males and females, there would be other obvious differences that, though not themselves linguistic, could have a differential effect on language development.