Hmm. This is not a productive conversation. Can we fix that?

Here are my concerns.

It's sounding like you have not worked much with genomics, given that you put "genomic experiments" in scare quotes, speak in terms of analogies with computer code, and don't seem to be aware of work in genomic archeology. We don't know exactly where random genes came from, but with mutation models we can indeed get some inkling about when a gene has arrived, and how it mutated. But your're acting like genomic archeology methods just don't exist, or as if you've never read even a paper in genomic archeology. Let me know if you want me to link you to papers here, that stuff is actually really cool.

You also ignored the idea that termination shock could help things get into the atmosphere, suggesting that you think about atmospheric entries in sciences fiction terms of "everything burns up", rather than considering all the possible physical trajectories that matter could take where it wouldn't burn up (especially if it's shielded by rock - more on this later).

You also make a bad assumption about the spores. They would need to survive millions of years in space, and they could have evolved in conditions much different from terrestrial ones, including in systems where space travel would have been routine.

You're also unaware of the xenobiological work here, and might not even think xenobiology is real biology. Namely, when you say there's no reason to think spores could survive space, you are either unaware of or discount the xenobiology work on spatial spores:

https://scholar.google.com/scholar?q=Panspermia%20spore&btnG...

For example, one of the papers in the list above suggests that 40 to 100% of bacteria would survive a planetary strike scattering them up into space. And that's bacteria! It turns out that tiny things are very very resistant against high accelerations, suggesting that spores might be able to make the landing too, especially if shielded by rock.

Then you're hand waving the idea that even if there was some biological contribution it would surely be wiped away by evolution and predators. Again, why? We're talking about microbes and fungi, which share their genes pretty prolifically. There are methods to look at a microbe population's genetics, backtrack the genes, calculate when they appeared and mutated, etc. A whole field of science you are just discounting.

There's there's no kind of precision to your hypothesizing, no citations or nods to existing work. It's impossible to have a scientific conversation like this - you are making pseudoscientific speculation of the kind that you're trying to fight.

It would be nice if you could say that you're not very interested in biology/genomics/xenobiology, and disengage the topic if you don't like theorizing, brainstorming, and consulting scientific literature. I understand that you are motivated to reduce the pseudoscience on HN, which is a noble goal. The problem is that you don't know enough science to tell science from science fiction / pseudoscience. And you're cramping my style, turning a potentially fun scientific conversation into pseudoscientific hand waving and muddling. I don't like that, and request a more scientific conversation from you if you please. We can have some kind of constructive and educational discussion if you want.

Either way I do hope that you have a good day!