And no, Nehru did not contributed the most, the whole of India was united by Sardar Patel with the exception of J&K which Nehru insisted on taking up. If you call that contribution ...
Understanding does not come by hiding ugly thruths. In India its a common belief (among Hindus) that Hindus have never done anyone any wrong and were mind their own business peacefully an then all shit happened to them. False historical constructs are dangerous. Study of clear and open history backed by grassroots records is super important. If you, your dad is in Pakistan now, here's greetings from near his older home.
Its importance varies by region though. Some parts haven't been touched by communal violence ever since partition (apart from Babri related ones) whereas others are repeat offenders.