way we look and the way we behave. in old age the environmental aspects become important again and determine how physically and mentally fit we are. twins with the same genetic makeup can develop differently research shows that our genes are like hardware the software comes from lifestyle and influences which genes can be turned on and off to affect our development. and we can expect scientists to provide many more insights into the complex interplay between genes and environment. if you have a size question go to our website and send it in. if we answer it on the show you'll get our d.v.d. featuring a lighthearted look at albert einstein's most famous theories. the most important