This is just my opinion, but my 3 sisters look most like the following celebrities:

My older sister, Elisa, looks like:
Joanna Garcia (from Privileged - Ana brought this to our attention) and Courtney Cox (from Friends).

My younger sister, Mari, looks like:
Bibi Gaytan (a Spanish actress) and Jennifer Lopez.
My youngest sister, Ana, looks like:
Brooke Shields and Katie Holmes.