being unlucky in the genetic lottery. i want to talk to cnn chief medical correspondent sanjay gupta. sanj sanjay, peoples heads at home might be turning their heads. it's really luck genetic mutations you can control rather than environment, are we close tore a definitive answer now? >> i think so. and these are both big journals, the first as you mentioned was in science. this is nature. these are the important journals, but i think what they said in that first paper was that there is sort of an idea that there's some tissue, some areas of our body where you may be more likely to develop cancers because those tissues the cells divide more often in those tissues. and when cells divide that's -- every time it divides you get a chance of an error, a chance of a mutation. what this paper is saying, yes, that is true. but there's certainly environmental factors which play a much bigger role.