This section is from the book "The Transmission Of Life. Counsels On The Nature And Hygiene Of The Masculine Function", by George H. Napheys. Also available from Amazon: The Transmission of Life.
Undoubtedly, judicious marriages would eradicate al, hereditary affections. Legislation upon this subject is, of course, impracticable. Yet its importance demands for it the closest attention from the philanthropist and the moralist. The moral and social responsibility incurred, by marrying into a family of which one or more members have suffered from constitutional disease, is great, and should not be lightly assumed. Some general rules for the guidance of those contemplating such a union may prove useful to a few at least of our readers. Dr. J. M. Winn, an English physician, who has elaborately studied the nature and treatment of hereditary disease, has drawn up an estimate of the amount of risk incurred under various circumstances, as follows :-
"1. If there is a constitutional taint in either father or mother, on both sides of the contracting parties, the risk is so great, as to amount almost to a certainty that their offspring would inherit some form of disease.
"2. If the constitutional disease is only on one side, either directly or collaterally through uncles or aunts, and the contracting parties are both in good bodily health, the risk is diminished one-half, and healthy offspring may be the issue of the marriage.
"3. If there have been no signs of constitutional disease for a whole generation, we can scarcely consider the risk materially lessened, as it so frequently reappears after being in abeyance for a whole generation.
"4. If two whole generations have escaped any symptoms of hereditary disease, we may fairly hope that the danger has passed, and that the morbific force has expended itself."