Not because they are intellegent but because they are cunning and there is systemic bias and conspiracy by the brahmins who sit in DPC, interview board including UPSC to deny promotion and appointment to deserving candidates from under prievileged sections. UPSC interview for CSE is the biggest hoax. The marks obtained in interview often determines the rank of the candidates. It is seen some of the well networked candidates are given exceptionally high marks even though their marks in the written part is vey low. Further there is segreggation of the candidates as per their caste and accordingly the candidates are called for interview category-wise. Half an hour interview can not be an objective basis for judging a candidate. Let interview be held in camera.In fact whole procedure is so opaque. UPSC should bring down the total marks of PT to 100 from 300 immediately.