No answers like, “They’re all from Earth”, “They’re all in some version of Starfleet or United Earth Fleet”, etcetera.
My Answer
All three have stolen a Dodge-branded car.
In fact, Paris and Archer stole nearly exactly the same kind of blue Dodge Truck, Archer in ENT:“Capenter Street” and Paris in VOY:“Future’s End”. I found this out while browsing the Memory Alpha facts for the Enterprise episode.
Bonus if you can think of other weird ones.
They are 3 people who’ve never been in Cliff Clavin’s kitchen.