Income is measured easily and understood poorly.
A single figure says nothing about whether positions can change.
Two countries with the same gap can differ completely in .
In one, a child born poor has a real chance of ending up comfortable.
In the other, the was largely settled at birth.
Education explains much of the difference, though not all of it.
Where good schools follow the housing market, they the gap.
Where funding follows the pupil, they it.
Health matters as much and is discussed less.
A child who misses school for illness cannot catch up by working harder.
Policy that raises the works faster than policy that lowers the .
Both are political choices, and neither is a technical one.