health right now Closing the GAPS in your knowledge of YOUR FAMILY TREE can quite literally save your LIFE SARA McGREGOR never worried about getting breast cancer. Neither did her two older sisters. After all, their mother and maternal grandmother never had the disease.

THIS WEEK If we can rewind evolution to create a "snouted" bird, we might also be able to fast-forward it ARHAT ABZHANOV cuts a square hole in the shell of a chicken egg, drops in a small gelatinous bead and watches the embryo develop.

NEUROSCIENCE How can identical twins grow up with different personalities? "Jumping genes" move around in neurons and alter the way they work YOUR BRAIN IS SPECIAL. So is mine. Differences arise at every level of the organ's astonishingly intricate architecture; the human brain contains 100 billion neurons, which come in thousands of types and collectively form an estimate of more than 100 trillion interconnections.

Features Are you an orchid or a dandelion? Are you a sensitive flower or a hardier type? It may all be down to an intriguing set of genes, as David Dobbs finds out WHY are some children better at sharing than others? One attempt to find out uses what you could call the "Bamba test".