Oh man, this comment section is almost as hilarious as the manga.
First, Al's dad isn't beating him up constantly. Once, he decided to teach his kid a lesson and there's plenty of justification for it because Al does get into trouble often for saying too much. (And honestly, he just had him spar more intensely than usual, but since Al kept going on with the embarrassing nickname, having seemingly not understood a thing, he knocked him out.) For instance, he should not be saying Viscount Lolina out loud in any circumstance, even when the related person isn't there to hear it. If he keeps this up and ends up saying too much with higher ranked nobles, it's not just a single hit he might end up with. In other instances, like when Al took a pot without consulting anyone about it, his dad simply reminded him to ask permission beforehand.
Second, his sister definitely roughs him up too often, but the reality is that kids will do that. Give them a garden, lots of spare time, and they'll start throwing mud and pushing each other around or doing snowball fighting. She may hit him, but she's not beating him up, knocking his teeth out nor drawing blood. We don't see Al going around with bruises at all times. Those are light hits that are there because this is essentially a slapstick comedy. This comes with the genre. She will also intrude on Al's privacy and personal space because some family members are like that. I'm not saying this doesn't suck, just that it's not unrealistic. On the flip side, his family have shown plenty of times that they do care very much for him.
Finally, let's not forget that Al is a really mischievous brat. He's prepared an ice cold bath, a super spicy burger, and keeps dishing out burns even to people he meets for the first time. And in this chapter, he tried to fool his sister in a way that could never have worked because his sister had already heard his conversation with Silvio and knew he was awake. Mature is the very last term I would ever use to define Al.
Now, I'm not saying that this is what proper intimate contact should be, simply that this is what normally happens. More importantly, this is slapstick comedy and should be enjoyed as such. There's nothing shitty or abusive about the family, not by a long shot.