@Michael Harrop
I would do FMT some 3-5 years from now but I have some doubts:
While there are certain traits like emotional stability, working and visuospatial memory, which I'd like to improve, there are others that I very clearly
don't want to change
I don't want to lose my extreme intellectual curiosity, superb logical-analytical skills or excellent imagination because my FMT donor lacked such traits.
The microbiome DOES have a profound effect on mental, in addition to just physical health. However,
not in the way you imagine if you are seriously asking yourself questions like this.
I thought of this before my very first FMT (and before some other interventions before that)--I am on the autism spectrum, and a great deal of the unusual abilities that make me "me" have to do with being autistic. I wondered if fixing my microbiome could cause these to disappear, in addition to my health issues. But as I've done more treatments and become more experienced in how reality works, this is not
even close to what happens. And I've never read a FMT experience from anyone else where this was what happened either.
These basic tendencies and advantages and the fundamentals of personality are genetically and/or developmentally determined and pretty much set in stone very early in childhood--and while they are almost certainly correlated with the microbiome, this is because these inborn traits influence which organisms "take" within us. If by some chance we were exposed to microbes that would be most compatible with a completely different personality, they would have no hope establishing themselves within us.
It's plenty hard enough getting the microbes to colonize and stick around that we actually need in order to become the most functioning version of our existing self!
Obviously the microbiome isn't deterministically locked in though, otherwise it would never get out of whack and we wouldn't have to fix it with things like FMT. But that changeable aspect of the microbiome, what it controls is NOT our basic tendencies and strengths, but how functionally or maladaptively those basic tendencies play out, and whether we are more pushed forward by our strengths or more held back by our weaknesses.
I don't know if you saw the movie A Beautiful Mind, but if you did, you will probably recall the gap between when Nash was completely wrapped up in paranoid hallucinations and barely able to keep up with the basic necessities of everyday life like grooming himself and walking to class, vs. when he was able to be a brilliant professor winning awards and having a fulfilling relationship with his wife. This is the sort of transformation that's well within the capacity of FMT to bring about. Even the best FMT will NOT make a mediocre student, who struggles with math, capable of revolutionary works in economics--nor would any FMT turn Nash into a person with an average mind, neither by removing his gifts nor giving him some insight into the typical social world that he never had.
So the microbiome "slides" us all "up and down" on our own "personal scales"--e.g. for someone with ADHD tendencies from a spaced out klutz who can't do anything but play video games to a functioning creative professional. Each of our gifts have "shadow sides", and we also have just outright weaknesses as well that won't ever go AWAY, but the deficits don't have to be SO profound that we aren't functioning individuals who can use our strengths for something.
What you need to worry about when doing FMT is a bad one making your existent weaknesses
even worse. Like in your case, a FMT from the wrong donor could make you LESS emotionally stable,
further impair working memory, etc. In other words, what should drive donor selection is someone who doesn't exaggerate your existing ways of deviating from optimal. I suspect that these sort of problems happen when someone picks a donor who is him/herself above average in traits that the recipient already has too much of (like a low energy recipient using an unusually sedentary donor, or a hyperactive recipient using a high-active donor), but I haven't witnessed enough donor/recipient pairs to prove this.
So in summary--bad donors are NOT bad because they destroy the positive aspects of your existing personality if the donor lacks your best qualities. They either do nothing, or else they further amplify the
worst of your tendencies. Your existing tendencies are "safe"--but your existing trait profile MAY have a great influence on which type of donor works best for you
because it determines where your areas of greatest needs are.
