Just wondering. I thought it was Iris, but Roxie looks really young too. Iris is also technically a co-leader.
There is a bit of speculation as to who is the youngest. In Gen. 3, it is the twins Liza and Tate. In Gen. 4 it's Maylene. And in Gen. 5 it's Iris, who is 10 years old. If we knew the ages of the others, the answer would be much simpler.