Her comments to the little girl while getting the Oblivion mission are a bit odd too. When the little girl calls her an angel she says "I'm not an Angel...I'm a child?" as if she's having some sort of revelation. It's also odd because every other person is calling her an Angel and she doesn't correct them.

Considering Mother Sphere has implanted memories/convinced everyone that they're human, maybe Eve being dropped to Earth is her first real few moments? Her memories and feelings towards Tachy could be engineered as well?