The foundation of the LOCH story is the conflict between Gwok Jing and his would-be sworn brother, Yeung Hong. The deal made between their parents prior to their births was that if they were both males (which turned out to be the case), then they would become sworn brothers. If they were both females, they would become sworn sisters. If one were male and the other female, they would be husband and wife.
They were destined to become enemies, but in what directions would LOCH have gone if Yeung Hong had been a girl? It would certainly have complicated matters with Wong Yung and Princess Hua Jeng even further.