(Tl:dr: I study race in america, and black men and women are not actually larger or more masculine, that perception though is connected to the media and America's history with race. As to why it seems like there aren't many black women into extreme anal, in the end we don't know, though I do have some hypotheses)
HeyBaby, That's not really true :/ I study race and media in the US, this is actually part of a phenomenon called the "Masculinization of Black People" in which all black people men and women are portrayed as more masculine. (A similar thing happens to asian people except Asian men and women are 'feminized' rather than 'masculinized' by the media) For men this results in them and their 'huge barbaric dicks' (I love seeing BBCs fuck loose assholes as much as the next guy, but they are in the end fantasy) being fetishized, but this also leads to them being feared. Lynchings were often directly connected to the fears that southern men have that their women were irresistibly drawn to the ultramasculine black man.
While this to an extent made black men seem more attractive (though I think they would trade that in for a lack of lynchings) it did the opposite to Black women. Think about the media representations you've seen of black women, they're big, they're loud, they're 'ghetto', they're angry, they're masculine. This actually leads to a lot of black women being discriminated against in the online dating world, you can see this in a post the founder of okcupid made about the analytics of his dating website. (https://blog.okcupid.com/index.php/race-attraction-2009-2014/) You'll notice the same thing happens to Asian men, since as I said before they're feminized by the media.
Obviously though none of this explains why there seems to be (keyword seems to be) a darth of Black women involved in extreme anal. Though I do have my theories it's not my grad thesis lol
