mportance. Moreover, many supposedly
hereditary defects may equally well be the result of an unfavorable
environment like that which caused similar defects in the parents. Under
ideal conditions they might never appear at all. In such matters, too,
the best course is to consult a good physician. Often, perhaps usually,
the best thing is merely to avoid marriage with a person showing defects
like one's own, and then strive to give your children so good an
environment that only the best in them will have a chance to develop.
Fortunately the vast majority of people inherit a fairly good
assemblage of traits which balance in such a way as to produce normal
human beings.

One type of deficiency, however, renders people genuinely unfit for
marriage. It takes various forms. One form, easily recognized, is what
is commonly called "mental deficiency." By this we mean not merely the
kind of mind found in idiots and imbeciles, but that which appears in
morons and other "high grade" mental weaklings. Such mental weakness, or
feeble-mindedness, is especially dangerous to society because it often
afflicts people who are physically strong and attractive, and who are
eager to marry. When such persons marry, they exercise little
self-control and are likely to have large families. In this respect they
are unlike mental defectives of lower types, who rarely have many
children and whose children are likely to die young. "High grade" mental
defectives tend to marry one another. The result is bad in two ways.
First, if the mental deficiency of one or both parents is hereditary, as
is often the case, children with defective mental capacity are sure to
be born, and will in turn produce other defectives. Second, even if the
defects of the parents are due to accident or disease, the children are
almost sure to be badly brought up.

The chief type of mental weakness is emotional in nature. Here is a
young fellow who as a boy was always a cry-baby and mamma's darling. He
is afraid to stand up for himself, afraid of athletics, afraid of girls;
and, because of all this, he is lonely, morose, and secretive. Here is a
girl of great ability and charm but subject to fits of deep depression.
Another young man loses his temper very easily and cherishes resentment
for a long time over trivial matters. The girl whom he is interested in
is extremely self-conscious and thinks that she is being purposely
slighted unless she is the center of everything. Others