I have always been annoyed at the idea that how diluted the solution is determines how long it lasts. The net amount that a person is exposed to should determine the effects.
If I'm exposed to 1 gram of 1% pheromone, that's 10mg of pheromone in my system. If I'm exposed to 1mg of 100% pheromone, that's 1mg of pheromone in my system. An undiluted spray has a better likelihood of delivering more pheromone given the same delivery, but the delivery system in the show was not very controlled. Getting sprayed straight in the face with a diluted solution should have greater effect than being doused with a 100% solution from several hundred feet up, where it has time to mix with all that air and have some of it blow away.
I don't think that a higher exposure to the point of becoming permanent would cause actual genetic changes, which would then be passed on to the next generation. I imagine that it would cause a permanent change to the brain chemistry such that the victim would never recover from the effects. The implication in the episode seemed to be that the greater the percentage of solution, the longer the effects would last. Realistically, though, I would think that the effects wouldn't last very much longer but rather would be more potent. Think about when you take one tablet of tylenol, and it lasts for 6 hours or so, but if you're in lots of pain, you take two tablets, which give you more pain relief but still only last about 6 hours.
