The only true RNG in the game is the output of the Casino. But that can be controlled through having Gloria unassigned and using the scroll wheel when here 8% bonus money appears.
So the stats aren't random, but you can't 100% predict them beyond the "high" "medium" "low" on the character cards.
Stats are pre-determined, although you won't know what they are till you buy them.
The difference between you're game and mine is that you've likely loaded an old save, which the new version isn't balanced for at all.
I don't know how loading an old save would have a character have a completely different stat spread, since I literally just downloaded and have played the newest update. Unless you mean that your save is from an older version then it'd make sense-
Aside from checking out the branching choices, I haven't reverted to old saves at all, and have played all the way through on just one version, the current one 0.9c.
I know the main girls are predetermined, and maybe a few of the earlier "generic" employees, like the tank basically having only fitness and almost no other stats, but a lot of your side-character's stats don't match between your game and my game.
For example your version of "Alex" has high fitness, medium charm, my "Alex" has high fitness, medium handiwork. Your "Caz" again has high fitness, medium charm, while mine has high fitness medium handiwork. Your version of Midori has high fitness, med handiwork, mine has high fitness, med intellect. Sophie yours is high intellect, med handiwork, mine is high intellect, med charm, etc.
Meaning stats for some characters is either a little random, as their scaling and base stats never change from the time you unlock them, or it's a version difference on your end.
Again, I've only ever played on this one patch. Just noticed that side characters don't always have the same main and secondary stat seemingly, or maybe some are random and some aren't, like your Than is the exact same as mine, but he's one of the few side characters with 2 secondary stats instead of one, so maybe he's an exception.
I don't know though. It's just weird is all.