What is the purpose of the short introductory statement?

Almost immediately in the first paragraph, Mandisa introduces her complicated relationship with her son. She denies her ability to control him in response to claims of her guilt in Amy's murder. This inability to control him started young, but really it started "from before he was conceived; when he, with total lack of consideration if not downright malice, seeded himself inside my womb" (5). Mandisa's relationship with her son is an important component of the novel, as it explains many of her motives as a character. Although she loves her eldest son deeply, she resented him for a long time when he was a child, as his birth meant the loss of her childhood. Later, Mandisa writes that the initial shock of her pregnancy has prepared her for this more vicious shock of Amy's murder.