[Physicist]

The trick is you or I could pick up genes from a virus (through some as yet unknown mechanism) that get inserted into our genome, which we could pass on to our descendants, but your genes would NOT have a common origin with mine in that case, nor would those of our descendants.

That's true, but it's in perfect keeping with common descent AND Darwinism.

Remember: Darwin didn't know anything about genetics. All he knew was that there is some mechanism of variation, and that some of those variations are passed to offspring. From Darwin's perspective, it doesn't matter whether a variation came from a single point copying error or a wholesale insertion from a virus, just so long as the change is inherited. For all he knew, the latter was the only source of variation; it wouldn't have changed the theory.

And the fact that YOU might have picked up a virus from somewhere--not that there's anything wrong with that--and acquired a gene that I lack in no way changes the fact that we share common ancestors.

But if you want to update your GEDCOM files at Ancestry.com to include your newly acquired parent, I'll understand. :-)

[muawiyah]

You're overlooking the fact that Darwin was obsessed with "sex" as the mechanism for passing along characteristics.

[stultorum]

"...the fact that we share common ancestors."

Could those ancestors be monkeys, by any chance?

I notice you conveniently did not say we "descend" from monkeys, but used instead the common Darwinist ready-made phrase, "share common ancestors." But we all know what you meant by that phrase -- ie, that humans descend from monkeys, whic is not true, btw.