By careful isolation of the hidden gene in all humans that gives us horns, just like these ones, or like, any horns you find... trust me, it's there, it's like a switch, but not like, on and off, but, 'weird horns' and 'crazy horns' and 'normal human head horns'. Well, let's not get into the reasonable technicalities of what makes sense and what doesn't, just buy my stuff.

Also see Jadrian's Black Marble Horns and my white Glow Horns.