that Dee hated that first house, and so Mrs. Johnson assumes that she will hate this house too. She is certain Dee "will want to tear it down." Dee had once written to her mother, saying that she would never bring any friends to visit them, presumably because she was so embarrassed by the family's home.

From these bits of textual evidence, we can determine that Dee's relationship with her mother and sister has never been good: as a child, she would seem to purposely humiliate them with her own knowledge and their lack of it, and, as a young adult, she was so embarrassed by them that she would never allow friends to see her home.

Dee left home to go to college and to pursue a more sophisticated life.

Dee’s mother does not really understand Dee, but she realizes that her daughter is very different.

Dee wanted nice things. … Often I fought off the temptation to shake her. At sixteen she had a style of her own: and knew what style was.

Dee is embarrassed about her family and their simple home.  The house they lived in when she was a girl burned down, and the family built another simple house in its place.  This is enough for her mother, but not enough for Dee.

She wrote me once that no matter where we "choose" to live, she will manage to come see us. But she will never bring her friends. 

When Dee comes back to visit, she tells her mother that she is now Wangero Leewanika Kemanjo and Dee is dead, because she cannot stand being named after people who oppress her.  It turns out that Dee is an old family name, but her daughter does not seem to care.

Dee does not just leave home, she turns her back on it.  She does not seem to care for her mother, sister, or home.  She sees everything about the poverty they live in, and nothing about the love.  She simply does not understand her family.

Mama says that, several years ago, she and the church raised the money to send Dee away to Augusta to school.  This was shortly after the family's first house burned down, some ten or twelve years before the start of the story.  The possibility that Dee actually set the house on fire exists because she was already outside when Mama ran out of the house with Maggie (who'd been badly burned).  Moreover, Mama recalls "a look of concentration on [Dee's] face as she watched the last dingy gray board of the house fall in toward the red, hot brick chimney.  Why don't you do a dance around the ashes? I'd wanted to ask her.  She had hated the house that much."  The fact that Dee was known to hate the home, to be so ashamed of it, and that Mama describes her as "burning [them] with a lot of knowledge [they] did not need" (just as Maggie was burned by the fire) makes it seem as though it is at least a possibility that Dee set fire to the home.  We might suspect, even, that this is what ultimately prompted Mama to come up with the money to send her away (though she only says that Dee was sent away to school after the house burned).  At the very least, Dee leaves home, ostensibly for school, but perhaps more likely because she was so miserable (and, maybe, dangerous to them) at home.

Dee left home so that she could venture out and find her true "identity."  She felt so helpless growing up in such an impoverished home.  She was popular, outgoing and also pushy.  She disliked her home and was ashamed of her family.  She was hoping that going off to college that she could assume a new identity.  She does this by changing her name and meeting other friends--such as her boyfriend, Hakim-a-barber.  They come back to her mother and sister's house to obtain some of the cultural items around the house to "show off her heritage" at school.

Mrs. Johnson says that Maggie looked at her sister (Dee) with "envy and awe." 

She thinks her sister has held life always in the palm of one hand, that "no" is a word the world never learned to say to her. 

Maggie is the one who is burned in the house fire. She is thin and, according to Mrs. Johnson, walks like a lame animal. Dee is described as "lighter" with nicer hair and a full figure. The implication is that Maggie simply had a more difficult time as a child and Dee, because of her determined personality and good looks, usually got what she wanted. And as much as Dee disliked the house and their living situation, she didn't hate her family. She simply wanted something different. This is why, after going to school, she would read to Maggie and her mother, giving them knowledge about other cultures, other ways of living, "other folks' habits." As the story unfolds, we learn that Dee is trying to get in touch with her African heritage but at the expense of ignoring her more immediate family heritage. So, there is the sense that prior to and after Dee left, she'd always loved her family but always wanted them to change (as she would) and become more "cultured." 

Dee left the house because she wanted to go to college.  She comes back not really understanding her heritage.

Dee is not like her other family members.  She always wants more.

Dee wanted nice things. A yellow organdy dress to wear to her graduation from high school; black pumps to match a green suit she'd made from an old suit somebody gave me.

This extends to Dee wanting to go to college and go out in the world, beyond home.  When she returns, she has her own ideas about her family.

I didn't want to bring up how I had offered Dee (Wangero) a quilt when she went away to college. Then she had told they were old-fashioned, out of style.

Dee does not appreciate the quilts in the same way her grandmother did.  She thinks they are art, and does not understand that quilts are meant to be loved, appreciated and used—not looked at.

This story is an example of the disconnect between generations.  They try to pass on values and ideas as well as possessions, but it does not always work because the kids don't understand.