Here's an excerpt from the New Scientist article:
Fossils suggest the inbreeding took its toll, says Erik Trinkaus of Washington University in St Louis, Missouri. Those he has studied have a range of deformities, many of which are rare in modern humans. He thinks such deformities were once much more common (PLoS ONE, doi.org/p6r).
Perhaps this is the reason that monsters, gnomes, etc., are so common in our folklore and myths. They used to be much more common in our populations.
Check Scientific American c. mid-60s for an extensive article proposing just such anomalies caused by trauma, infection, nutrition, etc. during specific prenatal development periods. As I recall, the author was focused on the the Dark Ages.