WHAT MAKES US who we are? Scientific American Mind explores that question at many levels in each issue, and Vol. 16, No. 4, was no exception. Many people would intuitively say that we are all products of our genetics (nature) and environment (nurture)--and that the complex and subtle roles of each in shaping our inner selves provide endless fascination. The magazine's features also probed what we can do about who we are. In "Erasing Memories," for instance, neuroscientist R. Douglas Fields described how we might remove horrific events from our recollection. Is that a good idea? Your viewpoint may depend on who you are--and who you want to be. Other readers share their reactions on the following pages.