[EForEndeavour]

Also, my understanding is that the body position in rowing -- squat-like at the catch, with arms reaching far forward -- impacts breathing to the point that most (all?) rowers breathe twice per stroke at higher stroke rates, such as race pace. Your dad and brother might be optimized for faster, relatively shallower breaths.

[beenBoutIT]

I rowed crew in college and swam on a swim team as a kid, IMO the big difference is that in swimming strategically holding your breath allows you to swim faster. With rowing there are brief parts of the stroke when breathing is physically impossible(right at the catch, as you mentioned) and you have to inhale/exhale around that. Outside of that rowers aren't deliberately holding their breath while rowing, ever.