A Shanghai family’s decades-long devotion to a vulnerable neighbour has led to the city’s first legal guardianship case involving people unrelated by blood.Ren, 71, inherited a quiet act of compassion from his parents, caring for his neighbour Xu, 56, for four decades, the Shanghai Law Journal reported.Xu was born with a mental disability. Originally from Xinjiang in northwestern China, he never married, had no children and has no surviving relativesHe moved to eastern China’s Shanghai in the 1980s with his grandfather, who died years later, leaving him to live alone.Ren’s parents, who lived in the same residential building, noticed Xu’s...