Yvette is half alien, half human. The non human half, Aforlatian, are totally
androgynous. Reproduction for them is typically done in with test tubes in a
laboratory. Miss Vignon’s Father was a human man, a Star Fleet officer, who ended up in an extremely odd relationship with the person that ended up being her mother. True love drove them to attempt a child, and a hybrid was born.  For the most part, she appears very human, though with a slight androgynous features but a deep sensuality.  From her ‘mother’ she also inherited the ability to project and direct emotions to other people. She grew up on Earth. Since can only project an emotion that she feels, she has spent time with the Vulcans learning to control her emotions.