Google is a wide wide place. And this is the result of boredom + curiosity. A French site has Emily's biography up, and it's interesting what it says in it.
She may be a very rare great-granddaughter of France's 11th president Paul Eugène Louis Deschanel. Crazy huh?
Paul was the son of Emile (!) Deschanel and was born at Brussels, blah blah a lot of history, he starts his presidency on February of 1920 but seven months later he resigned because of his increasing senile dementia. As Emily said on an interview, she knows about his history and everything buy they are no more than distant related. Although her grand father was a French engineer and emigrated to the US where he married an American woman with whom he had Caleb Deschanel (Emily's dad), he was raised under her Quaker religion and his dad died when he was a teenager.
It is also revealed in don't miss's site that her family is from Lyon and she often goes to it, but as I read in another interview (to which I don't have the link right now) she hasn't returned to France in almost 10 years. So...I guess that it's not that often that she goes.
Emily's biography @ dontmiss.fr
Paul Eugène Louis Deschanel @ Wikipedia
Caleb Deschanel @ wikipedia