My traps were the first thing to show up when I started cycling. My mom was the first to say something. There is definitely a genetic component to traps but I mean isn't that why we are on juice... to push past the genetic barriers?
I absolutely love working traps with my shoulders. I do all of my heavy compound shoulder exercises (arnold presses, regular dumbell presses,or barbell presses) first then I do high pulls usually 4 sets with a drop set on the first set. I really take my time on this first set of 8-10 (then failure on each drop while keeping form in check) 2 count on the way up squeeze 2 count down. Control the weight picture the blood being pushed into them when you squeeze. You will feel the fire. The last 3 sets will be straight hell to keep good form but when you can't do a full rep without cheating (this should be on the 5th or 6th rep) do 3-4 more cheat reps with a squeeze and fight the weight down on the negative. Then I finish my shoulders with 3 delt raise exercises.
Experiment with your back position (how much you lean over) on high pulls and position of your hands at finish (width and/or distance away from your body) let your body tell you what works best. Then switch it up.
Deads and cleans also work these but I don't focus on this area on those days ...just a bonus!!