ul to the offspring. A large
proportion of the children would probably die in infancy, and
the survivors be subject to some form of constitutional
weakness.

As there are few families entirely free from constitutional
defects of some kind, a prudent person would do well to avoid
consanguineous marriage in any case--not necessarily on account
of deafness, but on account of the danger of weakening the
constitution of the offspring. Remoteness of blood is eminently
favorable to the production of vigorous offspring, and those
deaf persons who have many deaf relatives would greatly
diminish their liability to have deaf offspring by marrying
persons very remote in blood from themselves.

Children, I think, tend to revert to the type of the common
ancestors of their parents. If the nearest common ancestors are
very far back in the line of ancestry, the children tend to
revert to the common type of the race. Deafness and other
defects would be most likely to disappear from a family by
marriage with a person of different nationality. English,
Irish, Scotch, German, Scandinavian and Russian blood seems to
mingle beneficially with the Anglo-Saxon American, apparently
producing increased vigor in the offspring.

CHAPTER VII

SUMMARY AND CONCLUSION

Having thus considered the more important problems which have been
connected with the marriage of near kin, we have only to discuss the
bearing of the conclusions thus formed upon the social aggregate, and
the effect which consanguineous marriages have upon the evolution and
improvement of the human species.

It has been shown that the frequency with which consanguineous
marriages occur varies greatly with the physical and social
environments; that such marriages are more frequent in isolated and in
rural communities than in cities; and that with the increasing range
of individual activity and acquaintance the relative frequency of
consanguineous marriage is decreasing.

Consanguinity in the parents has no perceptible influence upon the
number of children or upon their masculinity, and has little, if any,
direct effect upon the physical or mental condition of the offspring.

The most important physiological effect of consanguineous marriage is
to intensify any or all inheritable family characteristics or
peculiarities by double inheritance. The degree of intensification
probably varies