Upon hearing his father's words, Ling Chen's initial calm attitude was instantly and completely dispelled. He had an extremely serious and solemn expression on his face.
Even though he had never met his mother, he had long known that his mother wasn't as simple as his father portrayed her to be.
He wanted to read his father's memories so many times to see her for himself and find more clues about her origin but always changed his mind at the last minute.
He didn't want to invade his father's privacy. Though he didn't mind doing that to his enemies, his father was different. He even forbid Akasha to read his father's memories.
Nonetheless, he was still able to find many clues and concrete evidence by himself that proved that his mother wasn't as simple as his father, and most people thought.
First of all, his existence alone was a major clue that his mother wasn't simple. No regular humans could give birth to a freak of nature like himself.