Whereas some four year olds could draw a person with five fingers on each hand and a full set of facial features, others could barely hold a pencil. Some sat quietly in a small group, intently listening to and understanding a story, while others wiggled, fidgeted, and couldn't focus their attention. In those days, before the explosion of developmental neuroscience, the author's professors explained individual differences in readiness with the term "neural ripening," a catchphrase for the notion that individuals' developmental timetables differed biologically--and that there wasn't much one could do about it. For decades researchers tried to pin down what percentage of I.Q. is attributable to genes and what percentage to the child's environment. Nature and nurture are so intertwined from the moment of conception that it is impossible to separate them. It's a waste of time to try and determine an exact percentage of influence on any behavioral trait (such as intelligence or academic readiness). The issue is no longer Nature "vs." Nurture, but rather Nature "plus" Nurture. (Contains 8 endnotes.)