Yes. Even the simplest mechanics of genetics were misunderstood at the turn of the 19th Century. Most scientists believed that traits such as deafness were hereditary and that the chances of children being born deaf were increased if their parents were both deaf. The incidence of deafness was also more common then, before antibiotics were available.
In 2015, Professor William Ellis of the University of Iowa did a meticulous study of faculty writings and student newspapers at Gallaudet University for the Deaf and found that: “The idea that deaf people should not marry one another was embraced by faculty in Gallaudet’s early decades, diffused from administration to faculty, from faculty to students (deaf undergraduates as well as hearing students studying deaf education), and ultimately carried to other deaf educational institutions via the alumni. While student responses to these ideas were fluid, their adoption by early administration and faculty had a profound and lasting impact. One result was that, for much of the early twentieth century, deaf people were less likely to marry, and when married less likely to have children.”