Yes, nerd alert.
The gene that increases one's susceptibility to obesity.
It reminded me of an old documentary that I've watched... and at the time, they were still searching for the gene (FTO gene).
So basically it's comforting news for her.
He looks ecstatic =D
Just remember the gene just increases the chances of you getting fat, it doesn't mean it WILL make you super-sized.
Imagine someone stuffing his face with donuts while watching telly going, "Nope, it's not my fault that I don't exercise and live to eat."
More about the Fat Gene : http://news.ninemsn.com.au/article.aspx?id=109788