It is interesting how wide Osomatsu staff/Classicaloid staff (both are same staff) using family theme in various way,
In classicaloid season 2:
Sure, the characters are weird and eccentric enough to be real. Like yeah a hippo as a composer, a musik magic wielder men and women who treated each other as a family, then a troublesome kid who is up to something mischiveous come and mess up, making it a main conflict in this plot.
His reason? He is unable to accept himself for unable to be a musik wielder, and think that he is looked down upon, he feel like he is one of those 'brothers and sisters', the one who made him can't wield musik? His dad, or their dad. His dad flawed him because he sensed something dangerous, he flawed him to protect him. That kid suffer solitary, seeking acknowledgement by stealing others power and making him well know to fill that loneliness of unable to accept himself and felt like won't be accepted.
A parents love can be perceived wrongly, so his older sister came and slap him to a sense that he is always be a member of family, no matter how unforgivable his deeds and pranks are. His family try to bust in crushing his will to isolated himself from others, he imagined his version of his older sister to cope with his devastation after knowing his dad us the one who flawed him.
Also this is Bach's wish, one of family member, he wished for that kid, Wagner's happiness only, for him to enjoy himself with his power.
In Osomatsu san season 2:
Compared to classicaloid softy family type, Osomatsu san can be said as a crude and uneasy dark humour. It has family member being kicked out and the brothers are actors, which can be illustrated fake family like no one is actually love one another, it is just matter of fullfilling roles as family members. The other example is a hidden family secret for family improvement, to sacrifice others for everyone's sake on NEET rehabilitation episode but then a mother's love might let it go, love can also be a patience but can make someone weak-willed for improvement. It also remind us that a family remember may as well passed away and left us all, or so what we think for upcoming episode 24.
Other than that, it shows the sextuplets bros truly care about each other by scolding and accepting each other.