The colony contained about 500 breeding pairs and, averaged over the study's two years, herons caused the failure of 169 nests a year at the colony's centre, but only 92 a year at its edge.

ECONOMIST: Animal behaviour

The study looked at 1, 255 pairs of mothers and children from 1999 to 2002.

BBC: C-section 'may double risk of childhood obesity'

Mr Plomin has also set up a study working with 10, 000 pairs of identical and non-identical twins in Britain.

ECONOMIST: WHAT WE LEARN FROM TWINS

Not all secure high-flying jobs: many come to study, or to work as au pairs or waiters while perfecting their English, or to find a niche in London's huge creative industries.

ECONOMIST: The French community in London

One study, called the Achilles project, looked at 76, 475 pairs of feet belonging to people from 18 European countries.

ECONOMIST: Fancy footwork

In a recent study (published in the journal Public Library of Science One) seven pairs of subjects controlled virtual avatars.

FORBES: Body Language in Second Life

In a 2008 study, a group of economists tracked the wages of 60, 000 father-child pairs from 1978 to 1999.

WSJ: Downturn's Ugly Trademark: Steep, Lasting Drop in Wages

In the US study, researchers from the University of Southern California, Los Angeles, and colleagues identified 392 pairs of twins where one or both had Alzheimer's from the Swedish Twin Registry.

BBC: NEWS | Health | Alzheimer's risk 'is 80% genetic'