her hand, while we reckon habits, such as
profanity, or free spending, or an erect carriage, as belonging with
the acquired traits, we know that some natures are prone to certain
habits, and other natures to other habits. Thus the effects of
"nature" and "experience" are almost inextricably interwoven in the
behavior of an adult person.

Difficult as it certainly is to separate the native from the acquired
in human action, the attempt must be made. We cannot dodge so
fundamental a problem. Scientifically it is important as the
starting-point of a genetic study; we must know where the individual
starts in order to understand the course of his development.
Practically it is important because there is reason to believe that
native traits are deeply seated and not easily eradicated, even though
they can be modified and specialized in different ways. If a habit is
not simply a habit, but at the same time a means of gratifying some
natural tendency, then it is almost imperative to find a substitute
gratification in order to eliminate the habit. The individual's nature
also sets limits beyond which he cannot be brought by no matter how
much training and effort; and this is true of mental development as
well as of physical.

The Source of Native Traits

"Native" means a little more than "congenital." A child may be born
blind, having been infected by disease germs shortly before birth; he
may be congenitally an idiot because of head injury during a difficult
birth; or his mentality may have been impaired, during his uterine
life, by {91} alcohol reaching his brain from a drunken mother. Such
traits are congenital, but acquired. Native traits date back to the
original constitution of the child, which was fully determined at the
time when his individual life began, nine months before birth. The
"fertilized ovum", formed by the combination of two cells, one from
each of the parents, though microscopic in size and a simple sphere in
shape, somehow contains the determiners for all the native or
inherited traits of the new individual.

It is very mysterious, certainly. This microscopic, featureless
creature is already a human individual, with certain of its future
traits--those that we call "native"--already settled. It is a human
being as distinguished from any other species, it is a white or
colored individual, male or female, blonde or brunette, short or tall,
stocky or slender, mentally gifted or deficient, perhaps a "born