Her name is Mira she has made an appearance in the last published novel of FMP. And she is 16/17 years old like all the Whispered we have seen right now.
Kaname mother has died from a cancer 4 year before the start of the story.
From what we could see in the novel Whispered abilities are not inherited. Tessa and Leonard parents were completely normal and so are Kaname's, and Ayane, Kaname sister is also normal.
The Whispered perhaps are a genetic mutation but right now nothing say so.