Cnjussym:

After watching ep 12,  I think JiA killed her mother. I'm assuming the mother let the egg ghost possess her (or she dropped the talisman while fighting with InBoms uncle); and JiA stabbed her thinking that nothing would happen; not knowing that this method wouldn't work with an egg ghost and it would kill the possessed psychic for real (since it was the only way to get rid of that kind of spirit) :/

Omg that's totally it. It explains the stealing of the record, the false memory, why everyone wants to hide it from her.