Yeah, the "genetic" there isn't related to our chunks of DNA, it's there for "origin". Think on it as "the fallacy of the genesis of the argument".

When it comes to racism Lemmy is way better than Reddit, since the typical user here has better reading comprehension. In Reddit you can outright say something racist and nobody will bat an eye, as long as you avoid easy-to-spot words like slurs; here it doesn't work. Same deal with transphobia, misogyny etc.

You can use sources to strengthen a claim in a non-fallacious way, through inductive² reasoning. However, most people in Lemmy and Reddit don't; they want to eat the cake (use deductive¹ reasoning) and have it too (use the origin of a claim as part of the argument), and that's the genetic fallacy.

And, if I had to take a guess on why they do it, it's probably because:

• inductive reasoning doesn't allow you to claim certainty or knowledge
• inductive reasoning is messy, and it requires you to take multiple factors into account, to weight the likelihood of a certain statement to be true or false
• even when dealing solely with inductive reasoning, it's better to look at why the sources are claiming something than to use the claim directly

So inductive reasoning introduces a lot of complexity and doesn't let you vomit certainty. And yet both userbases are full of people who want to lie to themselves that they know something and that reality is simple.

And that's actually a big deal. Because, when you accept the genetic fallacy as solid reasoning (it isn't), you're opening the door to a lot of shitty manipulative tactics.

Notes/clarification:

1. Deductive reasoning: if you start with true premises, and follow a correct logic, then your conclusion will be always true. For example: X is always true when A is true. We know that A is true, thus X is true
2. Inductive reasoning: you basically "weight" a bunch of factors that increase or decrease the likelihood of a certain statement to be true. Even with optimal factors and reasoning, there's a chance that your conclusion might be incorrect. For example: *X is often true if A is true. X is sometimes true if B is true. X is usually false if C is false. We know that A and B are true, and that C is false, thus X is likely true." (emphasis on "likely")

I'll use some silly examples.

Ad hominem - taking a claim as automatically false because of who said it:

• [Alice] "The Sun is a star, like any other."
• [Bob] "People, disregard what Alice said. Alice is no astronomer, so of course the Sun is not a star."

Ad autoritatem - taking a claim as automatically true because of who said it:

• "See that scientist there? He has a PhD, and he claims that anthropogenic climate change is not a big deal. Thus we can safely disregard it as people making shit up."

Sometimes authorities are wrong. The likelihood of being wrong might be smaller than the one of a random nobody, but it's still there. You can't simply deal with it as "authority said so then it's true". (Check what I said about inductive logic in the other comment.)

There's more, but they all boil down to "you aren't analysing the claim, you're analysing where the claim is from".

One example that happens quite often is "look, Uyghurs are in forced labour camps in China", and the genetic fallacy response is "nooo that was reported by the New York Times which is an organ of western imperialism so it's all bullshit you're a westoid goon"