Edmund Owen, 1911 Encyclopædia Britannica, Volume 6… (1911)
“ Hare-lip is often associated with cleft palate. Though we are at present unable to explain why development should so frequently miss the mark in connexion with the formation of the lip and palate, it is unlikely that maternal impressions have anything to do with it. As a rule, the supposed “fright” comes long after the lips are developed. They are completely formed by the ninth week. Heredity has a powerful influence in many cases. The best time for operating on a hare-lip depends upon various circumstances. ”
