Can't we just drop a nuke on the Vatican

[Philippus Flavius Homovallumus]

Space Marines, Master Chief and Old Mans War... Aren't they all examples of why genetic engineering is a requirement.

I'm pretty sure in the 40k Universe humanity would have been wiped out without Adeptus Arbites and their mass produced spacemarine cousins.

In the Halo universe humanity would have been wiped out without the help of the Spartans.

So based on your examples I will do a Blackadder Xmas and thoroughly embrace genetic engineering as being a means to saving humans from extinction at the hands of aliens.

Point - but it's still pretty horrific tech.