I would like to mention that, the freedom obtained by us is not because of gandhiji, but because of Nethaji.
There were lot of unclassified documents, pertaining to india from 1937-1941, which are mostly destroyed in india, but a copy present in british archivals.
The main reason for britishers giving freedom is due to Nethaji's INA army. They could not believe, that the very indian soldiers to which they had given training turning against them. That inspired many of the presently serving army men.
But, the unpopular naval uprising took place in mumbai, when many of the INA soldiers were brutally tortured and executed.
This made restlessness in Army, where by 1946, most of the indian officers, did not obey their british officers.
Having looted most out of india, and nothing to extract more, the britishers did not have enough resource to replace the existing hostile indian army with their own one.
If if they did so, there was no benefit in doing so, because by 1947, india had been one of the poorest country.
So,they gracefuly exited before getting driven out by the well disciplined native army.
But they had their last say too.
Regarding your opinion on mahabharatha, no one said, wrongs did not happen.. Why karna was not allowed, is that on those days, a king should only fight against another kshatriya.. But, the context and meaning of the incident is highly manipulated.
Imagine, what would happen, if every one of the society started confronting the kings..
We need to see in the right context.
And for your query on inbreeding, i feel, the defective births were mostly happeneing only in the last century. Inbreeding, and endogemic marriage was normal for most of the time.
But, there are some rules over this. For example, in our community, i heard that marriage should be done only from families, which doesnt have any relations for three generations.. But that rules might have collapsed due to political and social instability and economic degradation.
But till 1990's, almost 80% of indian population had inbreeding, and the number of defective births seems to be negligible.
If you get chance, please read the book "Silent Spring" by Rachol Carson. Thats a pretty enlightening book.