The number of possible combinations of the human gene pool is said to be bigger than the number of molecules in the universe.

And this means that there always is an almost infinite variety of genetic information passed every time a human being is conceived.

Everything is possible. There can be males with full hair to their ankles, although they are of course rarer than females. And of all those males who could theoretically grow their hair to such lengths, only a tiny fraction will actually even want to do it. (The latter statement goes for women, too, by the way.)

And if you look at women, you will find a huge number who can never grow their hair beyond shoulder length, because it´s too thin and the ends will start splitting already. In this forum we only get to see those who make it to impressive lengths, which can by no means be taken for granted.

There is simply no end to what´s possible with humans. There is just no "invariability" with them.

There was this late American named Kim Peaks whose connection between the hemispheres of his brain was missing or at least severely reduced, enabling him to read a book simultaneously with his left eye down the lefthand page and with his right eye down the righthand page, and he remembered every detail afterwards.

Never underestimate human potential, whatever its practical consequences might be.