Dill Pickle Chips: We looked them up. They seem to be battered, fried Gherkins. We even found a recipe, so Katherine can make them at home.

Mitochondrial Eve is the nickname for a scientific theory that suggests everyone alive today shares a common ancestor through their Matrilinear line. A special kind of DNA is passed down from mothers to daughters; variations in that DNA lets scientists trace human migration patterns over thousands of years.

May 2008: Largest study of its kind confirms that breastfed children are brainier.

January 2008: Research suggests adopted Romanian orphans make up lost intellectual ground in 'loving and stimulating' environments.

How much does intelligence depend on external factors? This often gets called the nature v nurture debate. Intelligent parents (those with an above average IQ) are more likely to have books in the house and to consider learning important: two factors which can stimulate a child's intelligence.

According to a 2007 National Academy of Sciences study, children with one particular version of the FADS2 gene scored seven points higher in IQ tests if they were breastfed. But it’s not rare: around 90 percent of people carry this version of the gene.

Is there an intelligence gene? Behavioural geneticist Prof Robert Plomin compared the DNA of 50 children in the US who had high IQs with children of 'average' intelligence. Those who had high IQs were twice as likely to have a gene called IGF2R.

The question of researching an intelligence gene is controversial. Intelligence is almost always measured by IQ (Intelligence Quotient) test. But does doing well in an IQ test reveal anything other than you’re good at doing well in IQ tests? And what about external factors?

Haplogroups are groupings of tiny variations to a single gene within DNA sequences. These changes let scientists track changes and evolution across large populations. Check out this map of human migration over thousands of years, based entirely on evidence from DNA.