Why am I different?

I was bathing Isaac yesterday morning with Meredith's help. She was my helper holding the towel while I was bathing Isaac. When I clean up Isaac's private part, Meredith asked me what is that and why didn't she has it. I paused for a few minutes and quickly told her that Isaac is a Didi and Didi is a boy, and she is a girl. God made us all different and unique.

She just passed her 2 years old birthday in February. How am I supposed to handle her future questions!