Americans cannot draw anime

I am convinced, no matter how much wannabe-anime style art I've seen, that one has to at least have some Asian in them to draw the anime/manga style.  Yes, it's also cultural, but culture and genes go hand in hand.  The "L/R" misconception is actually the ear and brain processing the letters a certain way, and Japanese people are also more responsive to higher pitched sounds rather than low bass, as seen in a lot of their music.  So call me a eugenics Nazi, I don't care.

Most US or Europe art tends to have square or straight eyes, to denote seriousness or "toughness."  The anime round eye style seems to be a perception of femininity, a welcoming of it even in males, that allows the character to look naturally gentle or naive.  The sense of 2D moving fluidly in 3D is also different in some way.  US animators tend to focus on the whole body at once, from disney to Hanna Barbera to South Park to any show made for Adult Swim.

The closest thing to anime art is Pinup girls of the mid twentieth century (when females could be oggled without complaint) and some US comics, especially Image, but even these aren't pure manga style (they are unique, but some try to resemble anime). 

There is some perception of what a character "should" look like to manga artists, which creates the style, and can be seen in Korean anime style art where the heads are wider or more squished.  Somehow, the us perception of what a charracter should look like in 2D either ends up very two dimensional, or like Furry art.  Something in US artists makes a lot of them predisposed to drawing Furry art, or cartoon animals, but not humans.  Humans have always been the most awkward, strangest things to draw, and either must look photorealistic as in fantasy art, or be abstract and cartoony.

>>1 It certainly is not genes. You have not studied science if you think it's genetic.
Culture can explain everything in your list. Everything.

More things to consider:
- There were lots of "furry" Disney cartoons in the 80's and 90's to which Americans and Canadians were exposed at a young young age. This exposure creates a gut level reaction and ability to draw furry style. This easily explains its popularity!!

- You are grouping a lot of manga styles into one category. You've looked at the older 60's and 70's era manga, I'm sure? Quite a lot looks in no way similar to the modern sharp-and-angled style.

- European comics. It doesn't look american, it doesn't look japanese. What if Hergé's style were as insanely popular as manga? Would we ("we" because I am one of you) be striving to get it to look "right" and cursing ourselves for not being as good as the weird and exotic people of Belgium? Would we be able to tell instantly if a particular drawing were a genuine belgish creation, or a cheap US wannabe?
I think so. We would do that.

- You have, hopefully, seen spanish, french, and latin american doujinshi? They look exactly, EXACTLY like "real" manga, and trust me, I have as discerning an eye as you, if not more. These artists are not asian in any way, no asian blood, yet they draw well enough to even draw the notice of fellow artists in Japan.

In my view, the reason why Americans and Canadians cannot draw manga-style is because we have a different tradition of art. We tend more towards the abstract, the individual style, learning from scratch how to interpret the world on paper. We are immersed in, and trained from birth to hold, this mindset.

We are not trained to copy. We are not trained (except in certain graphic professions in the past) to study closely the exact technique and shape of a drawn symbol. We have no centuries-old tradition of artistic apprenticeship comparable to that of Europe, Latin America and Japan. (Not to say there haven't been artists produced comparable to those nations, but I simplify it.)

In general, then, we don't even know where to begin when attempting to emulate a style. And the few artists who can do it, must not be interested in manga or anime as serious storytelling techniques, although I wish it were otherwise.

Please >>1, look at what I have said and study up on the avenues of research I have suggested. It's fine to be a eugenics Nazi for genetic things, but in this case I do not believe it fits.