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.
A very pronounced philtrum?
The guys from Invincible?
Most aliens have forehead ridges; some, like Tandarand, have giant cheeks. But the humans, they have… pronounced philtrums!