"우리 어머니가 요리하시는 것을 싫어하세요."
Translation:My mother hates cooking.
Actually, to be more specific, in your scenario, if two siblings are talking to someone else about their mom, they would actually use "저희" which is an exclusive form of "our". Basically, it is "our" mom, not yours. But if one kid is talking to his sibling, then they would say "우리", i.e. "our" mom, yours and mine together.