Complex sentence: Although for much of the 1970s his mother was prime minister, and his brother Sanjay wielded significant unofficial power, Rajiv remained apoliticaleath in a plane crash in 1980, Rajiv reluctantly entered politics at the behest of Indira.
Split into simpler sentences: Although for much of the 1970s his mother was prime minister, and his brother Sanjay wielded significant unofficial power, Rajiv remained apolitical. After Sanjay's death in a plane crash in 1980, Rajiv reluctantly entered politics at the behest of Indira.