Conversation so far:
Who did Edmund Hillary marry?
Edmund Hillary married Louise Mary Rose.
What day did Edmund Hillary marry Louise Mary Rose on?
Edmund Hillary married on 3 September 1953
What did Edmund Hillary say about his first marriage?
Edmund Hillary admitted he was terrified of proposing to Rose and relied on her mother to propose on his behalf.
What are Edmund Hillary's children's names?
Edmund Hillary and Rose had three children: Peter, Sarah and Belinda.

Question: What was so special about them
Self-contained rewrite: What was so special about Edmund Hillary's children?