How can I make my mother and father understand that I'm just not the family type?

-My parents are fairly traditional. My mom works, but her main duty has always been us, and my father was the main bread winner and the one who gave the punishments, ect. They pretty much expect me to have children, settle down, be a homemaker, that sort of thing. Especially my mother. I've told them that I don't want children or to get married (though I have no prob with longer relattionships), and I plan to travel a bit. That's who I am. I'm not all that nurturing to begin with, and their's not a submissive bone in my body. They just kind of smile when I explain it to them and telll me I'll change my mind, she's the type of woman who kinda thinks all women want to be married and have children. I love my parents, but I don't get my mom. Between them, she obviously does more work, but gets less thanks. She has a job, does almost all chores and errands, and raised us for the most part. Sure dad makes more, but that's it, and not all that much more. I so don't want that for myself, it would be torture, plain and simple.. I'm going to move out next year, and I don't want her to be dissapointed or angry when she realizes I'm not going to do what she wanted, so how can I get them (mainly her) to understand? It's not that I'm looking down at the lifestyle, I just no I don't want it.