Why does Nepotism exist in Bollywood?

Due to this talented actors and actress don't get a chance to reveal their acting skills on screen. When I was a minor I had a dream of being a child artist but my parents said no to it because I won't get any success which is apparently true as those kid's of actors & actress will get chance no matter how bad their acting skills are. For example just look at Suhana Khan. I don't find her attractive or talented but still she got a chance in Maybelline and Lux Body wash ad and in Archies too!! It's all because she is daughter of King Khan and nothing else.