I'm writing a scene set in a small town in County Galway in the 1740s. My 17-year-old character is the son of a Catholic merchant. The family are falling on hard times. Can anyone tell me whether this character would be likely to speak to his family in Irish (Gaedhilge) or English? I know that both languages were spoken there at the time, and that Irish was more common, but I can't find enough information to establish the situation for this character.
For a bonus: would it be plausible for this character to be proficient in both languages?
Many thanks for any help you can offer!