Under such conditions, defectives would
be bound to multiply, regardless of whether or not the marriages are
consanguineous.
"It will be seen at a glance," Dr. Penrose writes, "that early in the
history of the Malone family these indications of degeneracy were
absent; but they began in the fourth generation and rapidly increased
afterward until they culminated by the presence of five idiots in one
family. The original stock was apparently excellent, but the present
state of the descendants is deplorable."
Now three generations of emigration from a little community, which even
to-day has only 1,000 inhabitants, would naturally make quite a
difference in the average eugenic quality of the population. In almost
any population, a few defectives are constantly being produced. Take out
the better individuals, and leave these defectives to multiply, and the
amount of degeneracy in the population will increase, regardless of
whether the defectives are marrying their cousins, or unrelated persons.
The family of five idiots, cited by Dr. Penrose, is an excellent
illustration, for it is not the result of consanguineous marriage--at
least, not in a close enough degree to have appeared on the chart. It is
doubtless a mating of like with like; and biologically, consanguineous
marriage is nothing more.
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