Nairobi, May 28 -- Duncan Onyango did not just grow up near a bank. He grew up inside one. His father was a Citibank man - old Nairobi Citibank, the original branch on Wabera Street, back when the lender was still establishing itself on the continent. Duncan remembers Christmas parties in the banking hall, he and his siblings running between tellers, the decorations, the noise of it.

Later, the parties moved to the CEO's home in Muthaiga. But the earliest memory is the hall. All that marble and money and quiet institutional power, and a small boy loose inside it, soaking in something he wouldn't be able to put a finger on for years.

What he absorbed was actually hunger. "There's this thing within you," he says, "which is just not satisf...