Well, to be fair, one of the working hypotheses about human mating behavior is that one of its goals is to equalize the biome of the female (bacteria, viruses, etc.) to that of her partner before she gets pregnant.

So, husband and wife having the same biome is not surprising.

And, even if you have the same biome, your systems will almost certainly react differently depending upon the expressed receptors.

Congratulations. You now understand why the folks trying to monetize microbiome are regarded as snake oil salesmen right now.

I'm sure there are broad strokes that are valid. You have a lot of bacterium X--that isn't good. You completely lack bacterium Y--that isn't good. Your overall diversity is low--you probably should try to correct that.

However, once you start getting into "you need specific bacterium X to solve specific problem Y", that's likely snake oil.

Biological systems are annoying like that. For any treatment X, there will be some, generally tiny, fraction of the population that responds to it.

The problem is finding a treatment that works in either 1) the vast majority of the population or 2) a readily identifiable minority of the population.

Microbiome work is probably going to produce some cool results, but it will take time to get there. Running experiments on people is time consuming and expensive.

I always pose the question - your gut was sterile when you were born, so how do you think the bacteria got their in the first place? The answer is oral-fecal transmission.

You get fecal bacteria on your hands, you touch an object, someone else touches it and they put their hands in their mouth.