[NineStarPoint]

Narrowing things down to “this group of people who live together” would be pretty useful forensically, I don’t really see a problem there. Has all the same issues DNA tests do on the “bullshit for the justice system to abuse” scale though yeah. Jurors will think “ah, science, must be accurate” when there’s any number of ways for things to get muddled in real life conditions.

[r2_pilot]

It doesn't even narrow it down to groups of people who live together. Consider this situation: your female dog in heat goes and seeks a male dog whose owner robbed a bank. She brings that microbiome contact back to your clothes when she returns. There could be a considerable distance between the two dog owners. Better hope you aren't apprehended or even better "It's not a search we're just patting this cloth against your shirt" in a drag net setting.

[KarlKode]

Or just going to a concert hall and having your coat hung right next to the bank robber or somebody who visited the bank-robber etc.