1.Indian media and books on Indira Gandhi says Rajiv's dad was Feroze Khan, a Muslim. Feroze's mother was a Parsee who had converted to Islam. They belonged to a place called Gandee. When Mohatma Gandhi came to know of this looming political disaster he arranged the name change,etc. BTW, the biological daddy of Sanjay was Yunus Khan, a Pathan related to Gaffar Khan. And in SA societies a child carries the name of the paternal family. So who were the paternal grand-parents?
2. Don't ask me to quote sources, because this shoiuld be known to Indians as general knowledge. There are innumerable media reports in India on this. One can Google and be educated. There are books also. One by M O Mathai, for instance.