I had the same kind of problem on my 32 spoke, 26" rear wheel, breaking more than 10 spokes in a year.
I heard it could be a spoke tension problem, even though they did seem tight enough and the wheel was true.

Then I bought a Park spoke tension meter, tightened them all up to the proper range (some were 10% to 20% too low).
Since then, I check the tension once in a while because some do loosen a bit over time.
I have not broken any more spokes, so I'm happy about that.