We believed in external influences on a woman’s baby, so we legitimized the idea of virgin births and racial purity
Let’s start with the idea of maternal impressions, the ancient theory suggesting anything a pregnant woman thinks of or looks at will impact her baby. Don’t laugh — we thought that way until the 20th century. There’s also something called telegony, which basically says a child is influenced by its mother’s previous sexual partners on a biological level.
Those two things helped shape the way we see a child who might not seem like they completely belong to their “parents.” The Daily Beast recounts the story of Madeleine d’Auvermont, who gave birth in 1637 — four years after her husband left town. At her adultery trial she proclaimed innocence, saying she had just thought really, really hard about her husband the night her son was conceived, and a miracle happened. It worked, and the child was officially made the cuckolded husband’s heir. It’s also how women have successfully explained away giving birth when they were supposedly virgins, or bearing children that are clearly a different race than themselves or their husband.
It also helped establish Nazi doctrine about racial purity. Since telegony was still a thing during the Third Reich, women who had already had relations with someone of an “inferior race” were deemed racially impure. The only way to get rid of the bad was to get rid of it completely — even Darwin said as much (via The American Scientific Affiliation). Thanks, Darwin.