What factors led to Linda not realizing she was a slave until she was six?

Life was quite "normal" for her until this time. In the first chapter, Jacobs (she calls herself Linda Brent in the text, but this study guide will refer to her as Harriet Jacobs) begins her narrative by explaining that she did not know she was a slave until she was six years old. Her father was a carpenter and she had a brother named William. She was indispensible in the household and became a well-loved personage in the community. Aunt Marthy had five children. Her youngest, Benjamin, was close in age to Harriet, so he was more like a brother than an uncle.

When Harriet was six, her mother died. The mistress she worked for was a kind woman and Harriet went to stay with her. This was a pleasant time and Harriet was taught to read and write. Unfortunately, this woman died when Harriet was twelve. After a week the will was read, and it was determined that Harriet would go to the mistress's sister's daughter Emily Flint, who was five.