"Real" brothers and "real" sisters

Sometimes you read about a man killing his "real" sister or stabbing his "real" brother. I used to be confused by this until I found that among illiterate Pakistanis and those who've studied in government schools, even distant cousins are called "brothers". So your "real" brother is one whose parents are the same as yours. In Pakistan no one uses the term "half-brother" or "half-sister" (when two people share one parent). "Half-brothers" are referred to as "step-brothers", which is a totally different thing. If you have a "step-sister", she is not biologically related to you and you can even marry her (this is because she is the daughter of a divorced or widowed woman whom your father later married). I once had a worker who asked for leave to go to his home town to be with his family because his "daada" (paternal grandfather) had died. He came back after a fortnight and less than a month later he again requested leave because his "daada" had passed away. When I pointed out that his paternal grandfather had died a month ago, he said that this time his "daada's" brother had died. For him, there was no difference between the two. This explains why government officials in Islamabad were fooled by someone named Aslam Jinnah who claimed to be the great grandson of Mr. Jinnah (whose actual great grandsons Jay and Ness Wadia are living in Bombay). In Pakistan, if you have a sister who has a great grandson, you also call him your great grandson. Once a woman (whom I'd never seen before) turned up at my door asking for financial help on the grounds that she was the daughter of someone whose paternal grandfather (“dada”) was distantly related to my maternal grandfather (“nana”). Of course I told her to get lost, but she created such a ruckus that the cops had to be called to silence her.