No one is exempt from general duties. And if I don't want to be bound by this promise-keeping obligation, I can refrain from making promises. But Thomson and English extend the volunteer theory to parent-child relations and abortion. And according to Thomson, a woman is not morally obligated to carry through a pregnancy caused e.g., by rape or birth-control failure, that she did not volunteer to undertake. Sommers argues in opposition to the volunteer theory but in agreement with Confucianism and Islam.
Familial duties are paradigms of special duties.
Sommers says, for example, that there are special duties towards one's parents, just because they are one's parents, whether one likes it or not. The question of whether or not you want or agree to have those duties simply doesn't arise. But as a general rule, one has duties to parents. Sommers also argues, as an extension of her view, that a woman might have special duties to a fetus, just because it is in one's body, no matter how it got there. I think she has interesting arguments.