Lots of pepper growers here so this thread should be good.
First the Morunga should have been hot, not just "wow thats hot" but "maybe that was a mistake... did I just poison myself... oh god what have I doooonnnnneeeee?!?!" Seriously its in that category of heat that isn't really useful for anything but biological weapons and cancer research. I cannot say what went wrong there except second what the pepper expert said, the hottest peppers need strong light.
Second I think both experts were right. Genetics are of primary importance (for a look into the human experience I suggest
The Bell Curve) when determining the differences in attributes. I can say that having grown multiple generations of the same peppers I only select the sweetest/tastiest/hottest from each batch and they have remained a consistently attributable across generations.
Finally, cross pollination is a really big factor with peppers. Experiment for yourself but I have put the mild banana peppers next to habanero to produce mildly sweet banana peppers with heat greater than the hottest jalapeno . Basically you have to segregate your peppers if you want them true to their genetics. In my dad's garden (he is crazy about the heat, more so than I) we have a front yard plot for the sweet/mild peppers and a back yard plot for the hottest peppers. What we have noticed is that the hotter peppers have a greater effect on the mild peppers. I have never noticed a hot pepper "weakened" but have several times had mild bells come out with a wonderful kick. My guess here is the sheer volume of flowers that the ornamental or hotter peppers produce vs. the lower numbers on the generally larger mild peppers.
-Ian