Complex sentence: He was the fourth and youngest son of the paymaster of the customs in the port, Nathaniel Coffin, who descended from Tristram Coffin, who immigrated to Massachusetts from Devon in 1642.
Split into simpler sentences: He was the fourth and youngest son of the paymaster of the customs in the port, Nathaniel Coffin. His father descended from Tristram Coffin, who immigrated to Massachusetts from Devon in 1642.