Little Miss and her 5 yrs of honesty

Picture this, I am in the shower, Lil'Man in his swing staring at me, Little Miss walks into the bathroom and says I have to potty. She uses the bathroom and comes out with a contemplative look on her face and then asks me "Mommy why do you have hair on your poepoe (code for vagina)?" UM, what to say what to say! Well, "because I just do" (great answer, I know) "when you are older you will too". Little Miss "When I am older like Layla?" (my 18 yr old niece). "Yes when you are older like Layla", "Does Layla have hair on her poepoe?", "Yes she does"! Should I give Layla a heads up encase the questions ensue?????? And the questions begin!