Easy there, cowpokes — if you didn’t know, “homogeny” just refers to things that are the same. It’s great for some things, like gears or screws of a certain size. In creative fiction, though, maybe not so much.
Take for example the lament of some critics and fans about the “Marvelization” of cinema. While I have my problems with blanket terms like this, I can see how people might come to the conclusion that the so-called Marvel formula, or at least characterization, has become a tedious mass of indistinguishable quippyness. It’s probably a bad example since I disagree and think the problem dates back at least as far as Joss Whedon, who definitely left his mark on Marvel but his style of every character being something of a one-liner machine can be seen on display as far back as the Buffy the Vampire Slayer series in the ’90s.
There’s nothing inherently wrong with this, but there is a danger of character losing their individual voice and that’s when homogeny becomes a problem, whether it’s flippant snark or Sesquipedalian Loquaciousness sounding out from a dozen different mouths. If one of the holy grails of writing (in my opinion) is being able to distinguish a specific talker without any prompts whatsoever beyond what they say, homogeny in dialogue is the opposite of that. Maybe it’s why George Bernard Shaw would constantly indulge in phonetic accents in his scripts, jes so yew would naow a cockney wuz tawkin’. On account of his characters otherwise tending towards being mouthpieces for his various philosophical musings of the moment.
Homogeny in dialogue is more than just potentially confusing or flattening, it threatens to be the absolute death knell of any entertainment: boring. Maybe not in the short run, but sooner or later people are going to become aware of a certain sameyness. It’s true that in certain friend groups and subcultures in real life people can end up sounding very much alike, but I think that’s where it behooves a writer to pick out the differences and figure out what makes Sorority Pledge A someone distinct from Sorority Pledge B. Unless of course, your intent is to paint them as a blob of a mob, which is arguably the case for me back when I was writing the “background” McCartys. But I knew most of them were going to have a (literal) expiration date, so I don’t think anyone got to know them long enough to tire of their schtick.
I guess the point is, as usual, to be mindful, and if you make a first draft and feel like your characters are just sounding like you, you might want to consider finding some variation. Hopefully not enough to sound forced in the other direction, but variety is supposed to be the spice and spice can do a lot to liven up the same ol’ and bland which doesn’t seem to have that kick you wanted.