What can i do for this?

well, when i decide to get pregnant later in my life, i always wanted a girl to be my firstborn. I want 2 girls and a boy, in this order. Are there ways for women to have a boy first or a girl first?? Like, does it depend on what kind of food you eat? someone told me that if you want a girl to be your firstborn child, to eat more dairy?? idk if that's true though.