Lin Manqing told you that many high-ranking members of the Spirit Sword Sect, even quite a few Heaven-Human powerhouses, are blood relatives of these women with special bloodlines.
"People are not plants; who can be without feelings?"
Many Heaven-Human powerhouses also don't want their blood relatives to suffer such a tragic fate, so they secretly send their descendants out of the Spirit Sword Sect to live as ordinary people in the mortal world. As long as they don't break through to the upper four realms and get sensed by the Heavenly Tome, the Spirit Sect, out of respect for the Heaven-Human powerhouses, would turn a blind eye...
During the conversation, you learned that Lin Qiushui's grandfather is an elder at the Heaven-Human Realm in the Spirit Sect.
