I think you should follow your intuition and gut and decide when you meet the families in the interview how much you want to disclose. Remembering of course that the parents want to know that their child will be getting all of your attention and letting them know that your child will mix in with the group well should help ease their concerns.
You don't have to go into great details or personal information about your family and your life, but it's important that your clients know that they can trust you and it's important for you that you choose parents who will be understanding and supportive and work with you. I'm sure you have enough stress in your life, so you need clients with huge hearts!