Kit grew up where slaves were a way of life, but she is repulsed by the thought of slave ships.

Growing up in Barbados as a member of the upper class, Kit is used to having slaves around to care for her needs.  She was not part of a big family, and never had a mother or siblings to take care of her.  When John asks her about her family, she mentions slaves as if they were a part of every household—because they were.

"Were there no women to care for you?"

"Oh, slaves of course. I had a black nursemaid…” (Ch. 2)

Kit never did any work.  She had slaves to do it.  It was just the way things were done where she came from.  It would never have occurred to her that slavery was wrong or to question it.

However, when Nat tells her that there could be people down in the hold on a slave ship, she is horrified at the very idea.  She has complained about the smell, and he turns on her.

Maybe you think it would smell prettier with a hold full of human bodies, half of them rotting in their chains before anyone knew they were dead!"

Kit recoiled, as much from his angry tone as from the repulsive words. "What are you talking about? People? Down in the hold?"

"I suppose you never knew about slaves on Barbados?"

"Of course I knew. We own-- we used to own more than a hundred. How else could you work a plantation?" (Ch. 2)

Kit asks him if they have slaves in America too, and he says that they do—to their shame.  He is proud of the fact that his ship never carries slaves.  She realizes she had never thought about how the slaves traveled from Africa “at all.”  She doesn't seem to have put much thought into slavery.  She is just as upset from the conversation as from the information.

When she thinks about leaving, she does feel bad about losing “the little African slave who had been her shadow for twelve years” (Ch. 3), because she had to sell her when she moved to America.  This seems to show some affection or attachment to her as a person.  She also resents doing housework, which see feels is “the work of slaves” (Ch. 7).  She is confused by life in the colonies, which includes so much hard work.

The travel to the colonies, and the new life in the colonies, is a culture shock for Kit.  Going from having slaves to doing the work they used to do certainly would be confusing and frustrating.  Kit’s attitudes toward slavery will seem upsetting to us, but for someone in her time period they would be natural and normal.