: What she is supposed to have done seems implausible but I couldn't say that
: it was completely impossible. If we lived in the haloverse and if L had
: modified human genetics... would we be able to detect her handiwork? After
: all, the genetic code is there for anyone to read.

: I suspect that we would have noticed something by now and I think that in the
: five hundred years or so that would follow, by the time of Halsey's
: work... I think that someone would have noticed.

: Given that Halsey is an oober genius and interested in genetics and the
: genetic potential of her Spartan supermen... I think that if anyone was to
: spot L's work it would be Halsey.

well we only recently mapped out the human genome; over the next five centuries I agree we would probably find anything that stands out, but it depends on people continuing to study our genes and our genetic code as a whole, which could have bumps-- war, plague, famine, having people that might otherwise have worked together going to opposite ends of human-controlled space, there could be laws banning doing certain things with genes...
also genes occasionally swap material; it could take a genius, a supercomputer, and some patience to figure out what they looked like 100,000 years ago-- you could study remains from that time, but they're not easy to come by, and you'd have to hope the DNA is still there and intact enough to tell you anything (here's and estimate of how fast DNA degrades that, no joke, they figured out by studying moa bones)

: Does she know of the Mantle? Does she want it? Does she approve of the
: concept? Agree with it?

I'd like to know this about everyone that has an idea what it is (which presently doesn't include me)

: Where do you think the story is going to go WRT H and L?

no idea, but that aspect at least should be interesting