Stephen Sackur talks to Rachel Dolezal, the ostensibly black American human rights activist whose life unravelled in 2015 when it turned out that she was the daughter of white parents. So what gives us our sense of who we are? Our upbringing and our communities both have a huge impact, but what about the most basic pillars of identity that we tend to regard as immutable? Is our racial identity something we can define for ourselves?(Photo: Rachel Dolezal talks to Stephen Sackur as part of BBC Identity season)