Aliens & Crossbreeding/hybrid experiments

I'm currently reading a book by Marc Davenport "Visitors from Time" and I came across a very interesting part within the book.
I think the author has a pretty good theory about aliens and their crossbreeding/hybrid experiments. I wish I could say the author is correct in the following quote but I thought it would be a good topic to discuss and get some views from others.



The most popular theory to account for UFOs proposes that they are extraterrestrial spacecrsft piloted by beings from other planets. But, as every geneticist knows and everyone who remembers his high school biology lessons can guess, the idea that life forms closely resembling humans could have evolved independently on another planet is at best highly unlikely. And the idea that such life forms could mate and crossbreed with us is patently absurb. We have been creating hybrids for centuries now. We know that only species with relatively recent common ancestry- i.e. those whose DNA molecules are substantially identical- can be crossbred. Horses and donkeys can interbreed, for instance, to produce mules, but men and chimpanzees (whose genes are only 99% identical) cannot. The chance of a species with DNA nearly indistinguishable from ours evolving independently on another planet constitutes such an astronomical improbability that there is no scientific choice but to consider it impossible.
Since it has been well established that the witnesses are not lying, we are left with only a few explanations:
(a) We and those ufonauts who interbreed with us have a common ancestor (or were created with identical genes)
(b) They are human
(c) For reasons we do not yet understand, evolution results in DNA structures, even if it occurs independently on other planets.

Highly unlikely that we could find a species with which to breed....they may not even be the same substance as us....could be made from....water
It would be interesting to see what would happen if we COULD breed with aliens...

Well, for a or b to be possible, they had to have started here and left, which really isn't possible, or we started elsewhere and came here, which is possible, but very unlikely. As for c, well that's an absurd assumption. There are probably similar structures, but I'd be weirded out if aliens DID develop DNA as we know it, and lived under similar conditions.

Since it has been well established that the witnesses are not lying

I think there's the source of the inaccuracies.

(d) they are humans, but humans traveling in time from the future and so have diverged genetically to some degree

(e) they spent a very very long time with high technology to get the biology to work

Right now we can insert single genes from unrelated species. What that conceivable
30 or 50 years ago? Right now, we have just about decoded the human genome---but we
are just at the beginning of understanding the stupendously complex interactions between the molecules produced by the genes which result in life. Look at the publications that have been done in molecular biology of 20 years (100,000s, maybe millions). Now imagine how much molecular biology could be done in 10,000 years. Consider that humans may not be their first non-native species they've interacted with. Maybe they had 20,000 years to practice on other mammals, or other animals on other planets.

They might have giant eco-parks of foreign species (to them) so that they can, say, breed billions of lab mice and rats to learn about foreign planets' biology.
It may be possible that they can breed non-fertile 'mules'.