Well, as far as we know, thanks to the world expert when it come to futas, the Dr.
Icarus Media , and his numerous peer reviewed publications, Futas are "X*".
Like for the X and Y chromosomes, the * chromosome is named due to its shape. The two extra branches carry the genetic material needed for a living organism to deal with high level of both estrogen and testosterone.
By default, the hormonal level is, relatively speaking, bounded. If the level of estrogen is high, then the level of testosterone will be low. This whatever the sex of the person. If a female have a higher than the average level of testosterone, you'll notice that her level of estrogen is also lower than the average. And vice versa, a male with a higher level of estrogen will also have a lower level of testosterone.
But the * chromosome raise the hormonal limit, what explain why futas have a high enough level of estrogen to grow feminine traits and attributes, while also having a high enough level of testosterone to grow masculine traits and attributes.
Their personality itself being then defined by the hormone with the highest level. Most of the time it will be testosterone, and you'll face a horny, if not nymphomaniac, futa, aggressively seeking for breeding. But in around 5% of the births, it's the estrogen that will be dominant, and you'll have a docile and slender futa, who'll be more than happy to be used anyway that will can please you.
This being said, and to conclude the debate, in a recent publication, that have still to be reviewed by peers, Dr. O'nymous
(oh, it's me), pointed an important point. There's a masculine traits that is only exceptionally seen, around once for a million studied cases, in futa: Excessive body hair.
Futa do not have chest hairs, nor do they have beard. Two characteristics that, beyond the sole genitals, are an undeniable male characteristic. Therefore, peoples claiming that futas are males are missing the point. Futas are females way before anything else, and any intercourse between two persons of opposite sex can not, by definition, be homosexual.
It's hot, I'm on holidays, and was a bit bored...