I am almost positive Emily's mother also has DiGeorge. And the Parkinson's is a more recent diagnosis. DiGeorge does come with an increased chance of early Parkinson's.
I don't think Emily's mom is really a bad person. It sounds like she dealt with a lot of mental issues and some diminished capacity, got knocked up, and tried her best but because of her own limitations, she just wasn't able to take care of Emily and her brothers. I mean, Emily would be a handful for any parent, let alone one with their own issues.
Did her mom have some fuck ups? Sure. But it seems to me like she at least tried to make improvements in her life (and the kids by giving custody to Emily's grandmother) to the best of her abilities. I don't think I've seen any proof of her mother being outwardly malicious and cruel like Emily.
Emily on the other hand, will never ever try to actually make her life any better. Shit, she can't even improve her doodles.