We have been invited to view “Traces of the Trade” at the Church of the Incarnation.  First-time filmmaker Katrina Browne makes a troubling discovery — her New England ancestors were the largest slave-trading family in U.S. history. She and nine fellow descendants set off to retrace the Triangle Trade: from their old hometown in Rhode Island to slave forts in Ghana to sugar plantation ruins in Cuba. Step by step, they uncover the vast extent of Northern complicity in slavery while also stumbling through the minefield of contemporary race relations. “Traces of the Trade” offers powerful new perspectives on the black/white divide.