Genetics is going to play a role, I dont have the triceps of my dreams either. Paul Demayo had some of the best triceps ever IMO, but it just doesn't work out that way for me, at least yet(?)
I do 2-3 sets reverse grip benches heavy, low on the chest of course, ~4 sets skull crushers, and then 1-2 sets of kickbacks or cable pressdowns, or one arm overhead dumbell extentions.
Whats your routine look like?
Look at Markus Ruhl, freakish biceps, not much in the triceps department.