Here is one thing that came up after googling: https://www.nytimes.com/2003/11/25/science/q-a-twins-and-all...
> In other studies, asthma, which is often tied to allergies, showed up in both identical twins only 20 percent of the time.
He may be able to get allergy shots to help treat allergies.
Anecdotally, I am Norwegian genetically, and it has been said that the scandanavians are the group that developed the gut biome to be able to eat cheese/dairy - and I eat a TON of cheese each year (and I suffer no ill affects (I’m super lean and tall and skinny))
Whereas one of my exes was Asian and would get IBS whenever she ate cheese.
Why would one need to "develop" a gut biome to eat cheese/dairy? Have you ever heard of breast-feeding? Yes, you may be surprised to hear that even Asians can breast feed.
What you seem to be thinking about is lactose intolerance, which is not due to a gut biome issue but due to genetic or environmental factor causing a deficiency of lactase, a protein, after infancy. Lactase persistence is not common in many ethnic groups.
There is evidence that a biome habituated to certain strains of lactobacillus can allow those that would otherwise be intolerant to become tolerant, but that has nothing to do with the cause of lactose intolerance.
> Whereas one of my exes was Asian and would get IBS whenever she ate cheese.
IBS is a functional digestive pain syndrome. It has nothing to do with lactose intolerance. For someone epeening about their medical knowledge, you seem to know very little to back it up.
adult lactase persistence in ancient skeletons in Northern Europe, Scandinavia, southern France and elsewhere.
https://www.npr.org/sections/thesalt/2012/12/27/168144785/an...
Lactose intolerance is an issue involving lack of endogenous proteins, not the gut biome.
Asians, all humans, except for rare cases can digest lactose in infancy.
IBS is a functional gut pain/dysfunction syndrome. Those with lactose intolerance don't get IBS when they eat cheese.
There is still a percentage of non-European population that can consume lactose into adulthood, and not break it down without any external symptoms.
Lactose tolerance is estimated at 30-45 percent.. So it's a substantial non-European population. The intolerance is heavily skewed toward East and South Asia -- though a lot of South Asians consume milk and paneer.
Let's say this is my area of expertise. I am informing you that lactose intolerance is due to a deficiency in the enzyme lactase, a typically endogenously (by your bodies' cells) produced enzyme. It is therefore not a component of the gut biome. The proteins in your body can affect the gut microbiome, just as the micro and macro structure of your organs can, but they are not part of the biome.
Lactase is present in all normal human infants, since all healthy human babies are capable of digesting breast milk. Lactase expression starts trailing off in toddler-hood. Some populations apparently developed a mutation that causes lactase to persist. One group are northern European/Scandinavians. But there are also other groups such as certain Africans and Meds/Middle Easterners that have lactase persistence (Mediterranean and Middle Eastern people have a long history of consuming sheep and goat milk). The interesting thing is that there are multiple, independent mutations.
The cause for lactase persistence has a number of hypothesis, such as the consumption hypothesis. But these are speculation.
There is no cure for lactase deficiency. The most common "treatment" is oral enzyme replacement. This is known as Lactaid and Lactrase. Lactrase seems to work better for symptoms in most people, but response is variable.