Abuse comes in many forms. In this case, it's obviously not physical abuse, but mental. If you grow up under mental abuse, you, well, accept it because you don't know any better. The only defense mechanism you develop at a young age is keeping your head down, since you don't want to attract attention to yourself. It's only later in puberty when you can compare to others that you realise something's wrong (which is when Sterling decided to run away). But by then, you can't even get fully angry (since that attracts attention and you're conditioned to lay low), so that expresses in passive-agressive, which Sterling uses.
As for the rest of the family, the problem with mental abuse is that it's hard to detect, since it leaves no physical evidence. They just could have interpreted as favouritism or the double standard for raising boys. Remember his sisters were also just kids at that time, while Ophelia also grew up in a dubious situation. Her father also pampered his daughters while being strict (and even giving up) on his son, so she might not have noticed any red flags. It's not like she supported her husband, more that she didn't know any better.
Okay, all that hit a bit too close to home for me (grew up with an uncaring, narcisistic mother) and is getting way too serious for a comedy game. Can someone bring the funny back, please?
