How are these reasons are similar?

Olinka believed that a girl's destiny is to simply become a wife to her husband. Check out this quote from the novel,

"A girl is nothing to herself; only to her husband can she become something.

What can she become? I asked. Why, she said, the mother of his children.

But I am not the mother of anybody's children, I said, and I am something.”

This underscores the rigid gender roles and subservience of women, especially Black women at the time.

Your second statement certainly marginizes African American's just as the first statement marginalizes women. Both speak to the systemic oppression of a group of people. Keeping them in ignorance ensured their low status.