How old is too old to breast fed

Ryan • I`m a nanny for two great boys. I also like to draw in my free time and plan on going to art school in August.
Ok I am not a mom so obviously I have never breastfed a child. I have however seen what happens when a 8month old is learning about his teeth with a bottle. I have seen a few shows where the child is like 7 or is homeschooled because they are still being breastfed. I am all for mothers wanting to breast feed their baby but at what point is the kid too old?