Yes he is from Pakistan and migrated to SA for better cricket future. In Pakistan there is lot of talent for cricket but due to corrupt system talent is neglected and players who have relatives in PCB makes it to playing 11. Imam ul Haq (nephew of Inzamam), Azam Khan ( the fat giant is son of Moin khan), Usman Qadir ( son of Abdul qadir) are few living examples of current time. Imran tahir has played 20 tests and 107 ODIs for SA, so it's a good migration for him.
This issue of nepotism is present in all of the South Asian boards and there is no quick fix solution. Even in the Indian team, useless players like Hard dick Pandya were retained in the squad for many years, despite not contributing either with the bat or with the ball. And in the end, promising youngsters like Venkatesh Iyer and T Natarajan finds themselves out of the team. Even from Bangladesh, I have heard about similar stories. But SENA nations are more professional when it comes to selection. Their selection polices are very unbiased.
I agree nepotism is big problem but not in team, instead its in management as far as Indian cricket is concern. So i think you're mixing nepotism with favoritism.
Guy like Pandya comes from very humble background and had virtually zero backing when he started his career. I don't like his personality at all when it comes to discipline, attitude etc but i can't point finger on him as far as nepotism is concern.
I have never seen nepotism when selectors select the National team and i admire this quality of BCCI because sometime local management neglect this very attitude when selecting Ranji, club team etc.
Venky and Nattu are talented players but i can't blame selectors because in recent time Indian bench strength is getting bigger. Its nice headache for cricket loving country but tough on selectors and they are bound to make mistake sometimes. Nattu was injured btw (surgery i suppose).
If nepotism is there like you mentioned then where are Arjun Tendulkar, Rohan Gavaskar, Binny etc?