To conclude that a belief is false by appealing to the origin of the belief is a fallacy.
You fail to understand how the conclusion was drawn - you are making hasty generalizations. It is not an
appeal to the origin, it is concluding that the supposed evidence presented is window dressing and that the 'origin' IS actually what most such folk are driven to argue in favor of in the first place, facts be damned.
It is easily seen on these sorts of forums - creationists often start out full of bombast and confidence, having read a creationist book or website or seen some youtube videos, and they are ready to DEMOLISH some evilutionist god-haters with their newly found "facts". In short order, the shortcomings of their position becomes clear (the argument via analogy to human activity for IDC, for example). They soon find themselves unable to counter rebuttals. They soon realize, at some level, that they are wrong, and so fall back on their Faith, presenting bible verses instead of even trying to discuss the science.. I have seen it hundreds of times.
"They believe in GodDidIt because anything else conflicts with their deeply held religious views."
That is what it boils down to for many creationists - in my experience, that is the underlying premise for nearly all of them, the attempt to argue 'science' is just window dressing.
For me, there came a point, about 20 years ago, when I stopped giving 'new' creationists I encountered the benefit of the doubt that their scientific arguments were potentially valid and that they earnestly believed that the science they were presenting damaged evolution and supported creation. I reached that point after engaging dozens of such folk, without a single example in which their science was valid, legitimate, meaningful, etc. After reading numerous creationist books and hundreds of essays on sites like ICR, AiG, the DI, etc. - nearly all littered with half-truths, misdirection, even outright falsehoods - all being unquestioningly parroted and presented as TRUTH by the creationist of the day. And upon demonstrating the errors of their claims, and the claims of their sources, getting only threats of damnation and the posting of Scripture in return. After that, I saw little reason NOT to employ, as you want to describe it, the genetic fallacy. But it was a conclusion based on experience, not a prejudicial or otherwise uninformed position.
Pretend that I believe that Jupiter is the largest planet in our solar system, just because I saw it in a cartoon, does that makes my believe false?
No, because there is empirical evidence for that which you could present if asked.
Were you to declare that Uranus was the largest planet because an ancient manuscript said so, and you were able to find some people with college degrees that agreed and had websites and books on the subject (all ultimately based on that ancient manuscript) and you entered a debate based on the information gleaned from those people, and your claims were refuted by those with real evidence, and you fell back on 'but this ancient manuscript said so!'...
What then?
Were I to describe that as 'he just thinks Uranus is the largest planet because of his devotion to some ancient manuscript', would that be a fallacy?
don't hide anything. There's no worldwide conspiracy. Small changes occur, and accumulate. If enough changes accumulate you have a "kind" very different from the prototype. There's nothing telling the changes to stop occurring so as to avoid too much change.
