These so-called quantitative traits are under the control of a number of different genes acting in concert as opposed to qualitative traits such as human eye colour, where a difference in a single gene produces a single, sharp distinction.

ECONOMIST: A genetic game of chicken

If the difference in weight matches one particular amino acid, gene-sequencing can be bypassed altogether.

ECONOMIST: Viruses: Hunt the mutant | The

Study of these fragments showed that they sometimes differed from one another in three places along the length of the gene although this did not prove that any or all of those variations caused a difference in coat colour.

ECONOMIST: The genetics of mammoth coat colour

Two stand up comedians, united by a common interest in all things scientific, we know that the difference between the sexes doesn't boil down to shopping and map reading, but to the SrY gene.

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