Epigenetics, or "why I got fat"

So following on from the programme on graphene was another fascinating Radio 4 show, this time about epigenetics. There's a huge amount of material available online explaining what this is (try this BBC Horizon link or this news item on the link between epigenetics and obesity, or there's always Wikipedia) so I don't intend to go in for a huge long explanation here, but simply put epigenetics is the idea that it's not only your genes that control how you develop but also the effects of external environmental factors on your genes. These factors can turn genes on or off and are especially influential during foetal development or, in males, before sperm start to develop.

A boy's environment, behaviour, nutrition, etc can affect the gametes and effect changes not only on that boy's children but on his children's children.

Of particular interest to me was the statistical revelation that a father who started smoking before reaching the age of puberty was much more likely to have children that were fatter than average in later life.

So it's nothing to do with all the pies I've eaten! It's because my Dad started smoking when he was eight!