The way Theosophists and their Buddhist teachers spoke of skandhas (cf. The Mahatma Letters) as karmic operators within the shells of the dead is quite close to how modern science have found genes operating. If genes can not be said being the very same thing as skandhas, they surely seem to have an operative connection to them. In genes we carry very concretely the karma of our own as well as our blood ancestors. Intergenerational trauma and epigenetics are some of the fields where science have observed these things, while we as occultists may start to look at the more subtle and abstract operators where genetic material may be only the last links in the chain of karmic law taking place. Or so it seems when we think of a medium connecting to these shells of the dead and messing with their skandhas. Surely they are not messing with their material dna structures from afar? Well, it could be the case as the dna chains do take quite a long time to completely disappear and spatiality is perhaps to a degree transcended in the abstraction where we operate with more and more subtle things to the point that we start to operate with spirit. Here we have another window to how crucial ethics and karmic operation are in reaching to the spiritual and bringing the spiritual aspect in to operation in rituals etc. At least for me, the most potent ritual magic has been deeply rooted in healing the results of my own misdeeds.
It is interesting that the Theosophists' most accute and sharpest end of critique on mediumism was questioning the ethics of getting the skandhas of the dead mixed with those of the medium (not to forget the critiques foremost relevance to spiritual evolution!). I wonder how this reflects on the ethics of genetic manipulation. The most problematic thing there seems to be that manipulating the last link in the chain closes the interface where this specific karma becomes visible and translatable to the human beings and thus it can be harder to take responsibility of something which you can not see but it affects your life from behind the misinforming facade. The presence of ancestors in such a case can be seen poltergeist-like, something that has been ripped away a connection to the world and might sometimes in its anxiouos dark hovering behind the surface make the objects move violently. But ofcourse, being powerless - without blood and flesh -, it can not do such a thing without the help of human operators.