I'm trying to translate into Japanese for an academic paper a quote from a 19th century eugenics book into Japanese. It contains the phrase "Those with lower ideals will continue to restrict their families, and, with the weaker and unsound stocks, will weed themselves out of the race."
I found 虚弱体質である、身体が虚弱である、身体が弱い、病身である for "have a weak constitution"; 体質が健全だ、体格がいい for "have a good constitution"; and よいしつけ、正しい作法、育ちの良い for "of good breeding".
However, none of these include the English nuance about animals that are in the words "stock" (as in "livestock") or "breeding," which I think should come across in a book written by misled eugenicists who considered some human families to be quality stock and others to be low quality stock. I'm looking for a word in Japanese that could be used to refer to humans but is largely associated with the idea of animals as a lower species. To refer to the people who the authors thought should die off as 方、者、or 人 seems like the demeaning nuance would be lost.
My translation so far is as follows, with the spots for "stock" marked by blanks:
"[T]he realization of the power of limiting the birth-rate . . . [means] [t]hose who, sound in body and mind, possess a high moral tone and a clear appreciation of their social responsibilities . . . will produce many offspring. Those with lower ideals will continue to restrict their families, and, with the weaker and unsound stocks, will weed themselves out of the race."
(There are probably various grammatical errors in the translation at this point [1st draft] so I apologize for that [any tips on improving it as a whole would be gladly welcome as well].)