Quite often, the microbiomes of families or co-inhabitants share similar properties because the external factors such as exposure to pets, household microbes and meals are the same.  There may be overlap in the species and strains present, but differences in the amount of each.

Recommendations for foods also may seem similar, but may have been selected for different reasons for each customers microbiome.  Most foods have a complex number of properties, and will be of benefit to the microbiome and host for different reasons.