Emily Benn, who will contest Croydon South for Labour in May next year, insisted that her famous surname was not the reason she was selected for the seat.
Ms Benn, 24, who was elected as a councillor in Croydon earlier this year, faces an uphill battle to join her uncle Hilary Benn in the Commons - she will have to overturn a 15,818 Tory majority to take her place on the green benches.
It is not her first attempt to enter the Commons. She lost in the battle for the East Worthing and Shoreham seat in 2010.
Prime Minister David Cameron attacked Labour's political dynasties earlier this year, with Jack Straw's son Will and Lord Kinnock's son Stephen also seeking election.
In the Commons last month he said: "It is the same families with the same message - it is literally the same old Labour. That is what is happening."
But Ms Benn said it was "insulting" to the local party to suggest her selection was for any other reason than her abilities as a would-be MP.
She rejected the suggestion that her ancestry meant there was extra pressure on her: "The pressure and responsibility comes from the people who voted for me as their candidate and from Labour supporters."
In 2010 the seat was won by Tory Sir Richard Ottaway, who is standing down next year, with Labour in third behind the Liberal Democrats.
Ms Benn said: "It''s obviously a challenge for Labour, but I firmly believe that there should be no 'no go' areas for the Labour Party."
As well as her uncle and grandfather, Ms Benn's great-grandfather William Wedgwood Benn and her great-great-grandfather, Sir John Williams Benn were MPs . Another great-great-grandfather, Daniel Homes, was also an MP.