Her name

Even though you may know this from chapter 4 how it shows Heidi's moms name I just wanted to point out that in the chapter on page 36 it has a list of thing's Heidi knows about her mom but on that list it only shows that Heidi knows only her mom's name. How come she only knows that much about her mother? Do you think it's because of her moms mental disability and her mom doesn't really tell Heidi a lot of stuff about her self. Or do you think it's because of something else. What do you think?