A bell curve is a graph where data is shaped like a bell. Many measurements in real life have a symmetrical distribution pattern that resembles a bell curve - formally known as the ‘normal distribution’ or ‘gaussian’ curve. A bell curve distribution shows the majority of a population to be concentrated around the average and fewer people located at the extremes.

The most common plastic surgery procedure in East Asia, in which a crease is created above the eye to produce a double eyelid.

Deoxyribonucleic Acid is the chemical that genes are made of: the agent by which genes operate and are inherited, the instruction manual for every living creature from viruses to humans.

The term ‘Eugenics’ was coined by Sir Francis Galton and in 1904 he defined it as “the science which deals with all influences that improve the inborn qualities of a race; also with those that develop them to the utmost advantage.”

In the 1920s and 1930s Eugenics was presented as a mathematical science that could accurately predict how human ‘traits’ – like intelligence, hard work, cleanliness - were inherited. In countries like Britain, the USA, Germany and Sweden it became a popular social movement that believed in controlling human reproduction so that people with the ‘best’ genes would reproduce and improve the species. Fervent proponents of Eugenics brought about enforced sterilisations, euthanasia and ultimately, with Adolf Hitler and his followers, the Nazi concentration camps.

Genes are the orchestrators of every cell process, of every operating system in life. Genes come in pairs (except for those on the male Y chromosome) and during reproduction this pairing is split and the offspring gets a fresh pair - one copy from each parent.

The mixing of different human populations to produce a new ‘admixed’ population with novel gene combinations.

Genes are inextricably linked to the environment. Feedback between the two allows for positive and negative effects – depending on whether the environment is optimal or poor.

Genes come in pairs and often one is enough to do its job while the other is a ‘spare’. If both genes in a pair are non-identical they exhibit ‘heterozygosity’: they are heterozygous. Heterozygosity tends to be advantageous because two different copies of a gene allows for more environmental flexibility, especially if one of the genes is faulty.

A pair of genes exhibits homozygosity if they are identical. Homozygous genes can be especially disadvantageous if the gene is faulty. Both copies are faulty so the mutant gene is expressed as poor performance or, worse still, as a fatal disease.

IQ stands for ‘Intelligence Quotient’ and refers to a score given by several standardised tests that purport to measure cognitive ability. In particular, an IQ test measures mathematical and spatial reasoning, logical ability, and language understanding.

Population is the term used particularly by geneticists to describe a group of people (or any other organism) that share certain characteristics. The characteristic might be geographic origin, cultural background or almost any other feature.