why didn't I realize this before I got pregnant...?

Why didn't I realize that my brother and his girlfriend were horrible parents..? I used to be super close with them until I got pregnant.. After I got pregnant I look back at all the the things they've done.. Or all the things they haven't done.. For my niece and nephew. They haven't had any of their shots because they were too lazy to get out of the house.. They neglected both of their newborn babies, and she blamed it on "postpartum depression" and he can't keep a job because he's too lazy to get up in the morning and call in.. Every time I'd visit, I found myself caring for their children because they wouldn't do it... They didn't feed their children... And I feel so bad for not even noticing before I got pregnant.. Maybe I just wasn't paying attention.. I feel like an awful person.