@Gude YESSSSS! In my opinion they overreacted a bit
Spoiler!
They got mad because he "took their son's place", but that's not true. It would have been his soul in Arthur's body anyway, the only difference is that he has his past memorys. In all cases he would have been their son. And ok, he is a 31 year old man in soul, but so what? For all thoose years he was their son, he was never a perv, he did his best as a son, and gave his life for his family. Why does a past life interfer in anything? But it's just my opinion :)