Jean Duffney was one of three brothers who came to Nfld. He married Adele Adelaide Godet(Gaudet). In those days in order to marry a Catholic, he had to convert. The area he lived in was predominantly Catholic and he married a Catholic. His children were baptized and raised Catholic, as would be the tradition even if in today's time if he did not convert. It takes quite a lot of preparation to convert and whether it was a question of true faith or true love, we remain Catholic to this day.
Mixed marriages were not allowed in the Catholic Church for many years and sometimes are still frowned upon by dedicated Catholic family members who are faithful churchgoers and believers. Even in today's time, children of a union would be expected to be baptized Catholic. This I know from my own Catholic upbringing.