I thought your question was interesting, so I searched and found this:
https://www.anniesheirloomseeds.com/bhut-jolokia-ghost-pepper/
Although the website doesn't specifically mention if they're heirloom or hybrid, I'm inclined to think they're heirloom. First, the company above focuses on
heirloom seeds and sells the ghost pepper seeds. Second, the info states that ghost peppers originated in Northeast India. (So I'm supposing they have an heirloom pedigree?)
If all else fails, plant your seeds and report back to us your results. Ghost peppers are notoriously hard to germinate, though. But if you're successful, you might be able to breed a new-to-you ghost pepper variety!