adysav

For the benefit of those who couldn't be bothered looking, the above quote in context reads as follows:

Swedish psychiatrist Dr. Carl Olstrom has heavy experience in the
study of fetal deformities resulting from incest, and says that "There is
no evidence to support the assumption that children resulting from
incestuous relationships [with a father or mother] run a greater risk of
being malformed than other children."
Carl Henry Olstrom, M.D. Medical World News , February 4, 1967.

However, three much smaller studies showed serious birth defects in up
to one-fourth of all children that were a product of bloodline incest, an
incidence that is about fifteen times the expected normal frequency.
Mary Meehan. "Facing the Hard Cases." Human Life Review , Summer
1983, pages 19 to 36.

From the standpoint of pure eugenics, we must ask ourselves two questions; (1)
"Are handicapped people as valuable as those who are not handicapped?," and, if the
answer to the first question is "No," we must ask ourselves the second question:
"Are we willing to kill a minimum of three perfectly healthy children for every one that
may have a handicap?"

The fact is, nature doesn't actually know the difference between good and bad traits. Suggesting that nature 'selects' just bad traits to pass on is ridiculous.
Maybe you should become a counsellor at your local hospital. Every time a couple arrives with a chance of their child carrying a birth defect you can tell them that the only option is to have it terminated.