Where most countries wrestle with financial inequality through inheritance, in South Africa the legacy of apartheid means only a few South Africans see wealth pass from one generation to the next.

"Nobody owes you anything. Build your own wealth."

Every South African debate about race, wealth and opportunity eventually arrives at that sentence.

There is truth in it. There is also a dangerous omission.

Keep up with the latest headlines on WhatsApp | LinkedIn

The argument assumes that everyone began from roughly the same place, and that today's outcomes are explained mainly by today's effort. That assumption is comforting. It is also inconsistent with most of what economists know about wealth.

Three questions are routinely confused in this debate. How much of wealth inequality is explained by inheritance? How many rich people inherited their wealth? And how much advantage comes not from inheritance itself, but from the privileges wealth creates - good schools, professional networks, stable families, financial security, social capital? These are different questions, and they have different answers.

Across advanced economies, economists comparing France, Spain, Britain and the US estimate that inheritances and gifts alone account for roughly a quarter to a third of wealth inequality. Add the rest of family background - parents' education, occupation and social position - and the combined contribution ranges from more than a third to almost half.

Sit with that. In these economies, between a third and a half of the differences...