Fat Family Tree sets out to unlock the secrets of an overweight family's genes, to help resolve their lifelong weight problems

The McConnon family from Stevenage have all spent their lives battling with their weight and failed time and time again to shed the pounds. Like lots of people they believe their family history of obesity could be down to their genes.

Mum Tina and daughters Lisa and Karen are all desperate to lose weight. Tina, who is a size 26 and weighs 15 stone 10 pounds, has lost both her own mother and her brother to weight related health problems and she's afraid that she's going to suffer the same fate. Elder daughter Lisa weighs the most: 22 stone and 4 pounds and is size 28. Lisa would really love to have a baby, but she has been turned down for fertility treatment due to her weight. Younger daughter Karen is a size 26 and weighs 20 stone, 13 pounds. Her biggest worry is that her own children are already starting to put on weight. They've already been teased at school for their size and Karen fears that, unless she can change, they could end up being obese as well.

Now, in Fat Family Tree, all three take a unique DNA test to find out if the genes they have inherited could help explain their weight problems. The test, devised with Cambridge University's Dr Giles Yeo, isn't looking for one 'fat gene'; it's looking for variations in more than 70 genes that can increase your risk of being fat in different ways. These genes influence how intensely you experience hunger, how effectively your brain detects the sensation of fullness when you've eaten, where in the body you're likely to store fat, and your sense of taste - giving some people a genetic preference for sweet or fatty foods.

Dr Dawn believes that, although she can't change the McConnons' genes, she can change their weight and their future by identifying exactly how their diet and lifestyle clash with their genetic burden. Fat Family Tree's team of experts now devise a unique, science-based, tailor-made diet designed to help the family beat their fat risk genes and lose weight successfully for the first time.