Our DNA is very similar to most other mammals on earth. We don't seem very alien at all.
Of course it's similar, but not completely.
We're hybrids!
Of course our DNA is not completely similar to other mammals, we're humans. That's how evolution works.
Then we agree here. Thork is the one saying it's similar.
You misunderstood. Our DNA similar to other mammals in the since that all members of Class Mammalia share DNA that expresses traits specific to that class. It's different in the sense that ours contains DNA specific to the Genus Homo and the species Homo sapiens. This is how evolution works, it's a gradual change in DNA that results in a new species. Having similar traits in upper classifications but more specific traits in lower classifications is indicative of common ancestry, not extra-terrestrial genetic engineering. If you want to argue that specific traits in humans are a result of extra-terrestrial interference, you'd have to argue that same in dolphins, octopi, and chimps, which all have a high level of intelligence. You could even argue that roaches, the immortal jellyfish, etc were engineered by aliens to survive. Another thing you'd have to deal with is proving that our DNA (or chimp, dolphin or octopi DNA) originated anywhere other than Earth, especially with this tasty bit of evidence.
http://en.wikipedia.org/wiki/Chromosome_2_%28human%29#Evolution