In Japanese anime, the vast majority of characters, male and female, are done by female voice actors.

Interesting. This depends on the expected audience of the anime, and whether most of the characters are young, right? I'm not an anime fan, but the movies I've watched (Ghost in the Shell, Jin-Roh, Mononoke Hime) have very distinct male voices. I've even heard from one reviewer that the Japanese love deep bass male voices in their anime, an observation which is true in my experience. They go as far as using deep male voices for characters who are visually or nominally female, such as the Puppet Master in Ghost in the Shell (pre the awful 2.0 remastered Blu Ray edition) or Moro in Mononoke Hime.

The Japanese language is fairly different from English, so much so that it can be synthesized so well that they have entirely virtual pop music stars.

https://en.wikipedia.org/wiki/Vocaloid#Singer_Library

Vocaloid's English support has gotten absolutely fantastic. If you're curious, here are a couple of my favorites: https://www.youtube.com/watch?v=EMc4kw45e5g https://www.youtube.com/watch?v=XmifuQvFu8M https://www.youtube.com/watch?v=cQKGUgOfD8U

They're not for everyone, and the voices are still mechanical, but I've become a huge fan of English Vocaloid, especially Gumi.

I don't think it's biological. I think maybe the industry was just bigger for males.

Take Tara Strong. Sure, lots of her voices sound a little similar (you might hear Timmy Turner, then hear the girl in Batman, and think "oh yeah, they do sound similar" once you knew they were the same voice). But she can definitely "transform" her voice.

The male voice actors on The Simpsons have incredibly transformative voices, which I think comes from lots of practice in the industry. The first time I saw a chart of all the voices for each character they play, I couldn't believe it. After paying very VERY close attention, I can kind of hear Mr. Burns in Moe, but just barely.

Harry Shearer often does voice impressions on his weekly radio show - http://harryshearer.com/le-show/

Edit: he also did a made-for-YouTube miniseries wherein he re-enacts actual transcripts from the Nixon White House tapes: https://www.youtube.com/watch?v=f9HtoWea72A