r or vigor of the offspring.
Unless that opinion is accepted as correct there is no reason for the
taboo now.[1719] Incest is, for us, a thing so repugnant that we
consider the feeling "natural." We may test the feeling by our feeling
as to the marriage of first cousins. First cousins are very commonly
married in England. Such marriages are under no civil or ecclesiastical
prohibition, and although many persons disapprove of them on grounds of
expediency, and parents might refuse to consent to them, they do not
come under the abomination of incest. In many states of the United
States marriages of first cousins are illegal. In Kansas they are put
under heavy penalties. We hear no preaching against close in-marriage.
The matter is not discussed. The limitations are set in the current
mores and are accepted without dispute. Evidently the only question is
where the line should be drawn. If it was proposed to forbid the
marriage of first cousins some discussion might be aroused. If it was
decided wise to forbid such marriages, it would take long for such a
sentiment of repugnance to be developed in regard to them as we now feel
in regard to the marriage of sisters, or even of aunts and nieces. In
history the movement must have been in the other direction. The
repugnance arose first and then became a ground for the rules.

+531. Human self-selection by taboo and other-worldliness.+ Laws against
incest and all caste rules which arbitrarily limit the number of persons
whom a given individual may marry may be regarded as blind attempts of
mankind to practice some kind of self-selection. Sex selection inside
the human race is the highest requirement which life now addresses to
man as an intelligent being, and the very highest result which our
sciences could produce would be to give us trustworthy guidance in a
policy of sex selection. It is not possible for some persons to dispose
of the life determination of others, as breeders control the union of
beasts. What is needed is that individuals, in making their own
decisions for their own self-realization, shall understand the whole
range of interests which are involved, and shall do what it is expedient
or necessary to do to satisfy them all. In times past men and women
have thus limited themselves by rules about incest, group and class
marriage, rank or caste, religion, wealth, and other considerations. In
every society there are traits which are approved and others which are
disa