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.
4-head, 5-head, 6-head
I’m going to go with receding hairline