There is a lot of evidence it is related, however that's not the same thing of course as being able to modulate symptoms via the microbiome (that one poop transplant study was extremely preliminary). I think the jury is still out on that latter idea, but current probiotics surely have no effect. I hope that as this line of research continues industry will adapt and we will start to see probiotics that are A) better at actually populating the gut and B) personalized.