What it's all about
Jean-Baptiste Lamarck's theory of evolution was that, bit by bit, stretching to eat leaves on trees, the giraffe passed on the acquired characteristic of a longer neck until it arrived at the gangly animal we see today. Then Charles Darwin put paid to this idea, writes James Williams.
Neither man was aware of DNA, genes or the precise mechanisms of inheritance, but both knew that features were passed from generation to generation and modifications took place.
In Identically Different, Tim Spector, a world-renowned authority on twins, introduces us in an entertaining and eloquent way to epigenetics - the study of how the environment can influence our genes and how those influences can be passed on to future generations.
Identical twins, Spector reveals, are rarely absolutely identical. Twins from the same egg can have different eye colour and be different heights and weights. Their personalities may also differ a lot. One could be heterosexual, the other homosexual.
Can athletes pass on their acquired talents to their children? Training can alter genes and, as Spector says, "some proportion of the changes to genes caused by exercising the muscles or the brain in adults could be retained as genetic marks, and passed on to our children to either use or waste".
Individuality, it seems, rules us more than a predestined, genetically controlled future.
Identically Different: why you can change your genes by Tim Spector is out now, published by Weidenfeld and Nicolson.
Compare Darwin and Lamarck's theories of evolution using jm2450's picture slideshow. bit.lyLamarck
Try rainbowhunter's PowerPoint for a guide to animal cloning. bit.lytesCloning.