@miyako19 I understand your viewpoint however my view of his family life is he always felt like he was walking on eggshells even though they were supposed to be supporting him as well.
I don't recall the exact instance but I remember the early chapters of him reliving kyouko acting out in his childhood and saying spiteful unkind things to him, on top of sealing his pain so he could withstand the bullying at school, the lost of his birth family and at least what always felt to me to be a firm rejection by his adopted family (sans dad who at least seemingly only wanted him for shogi) .
His home life from what we've seen wasn't abusive, but he was badly treated by his siblings and didn't feel like he ever belonged there and his big sister(at least if I'm remembering right) said to him no one would miss him if he ever died. And she continued to hit him with terrible remarks as he grew up at the beginning of the series. We didn't see either of his adopted parents really engage with him emotionally, and he seemed to believe that his living situation could snap and fall apart at any moment. He was openly blamed for things that were his father's fault and his adopted mother knew they were blaming him. I can't be angry at the kids for that but his adopted father's selfishness and devotion towards shogi meant he was neglectful in some real ways towards his family including Rei.
And then we started the series with Rei in a deep swamp of a depression caused by him having to sink or swim at shogi with his new dad knowing that it would bring him the bare faced hatred and cruelty of his new siblings and false niceties of his new mother. And if he couldn't live there, his aunt, his closest living family, would send him to an orphanage where who knows what could've happened.
No one helped him process his grief, no one even knew he was ignored and bullied at school, he was a veritable complete and utter social outcast in school and seemed to barely connect with anyone until the beginning of the series. And then he ran away from that house because the guilt and pressure crushed him and he couldn't take it. And then what do we have? A young man crushed by depression, guilt and grief.
I can't in good conscious call that treating a child well. I hope one day he has a conversation with them but whether that leads to anything I don't know. But one can live in hope.