This topic is a bit along the lines of the "Buddhism and science" thread, but I promise to keep it free of quantum mechanics. The field of research I'd like to direct your attention to is epigenetics, which is a relatively new branch of study in genetics. In a nutshell, epigenetics concerns itself with gene expression and the non-genetic aspects of phenotype development. Another way to put it is that epigenetics deals with heritable changes not based in the DNA. If this still sounds too abstract, think of it as the field that covers the gap between "nature and nurture". I think it is important for the public understanding of science, because the media and popular culture (for example the 1997 science fiction film "Gattaca") often give rise to the false idea that phenotypes -including human beings- are programmed from birth and entirely predetermined. If only we know how to deocde the genome, we could predict at which age we come down with what disease, for example.
Well, this idea turns out to be not only in discord with Buddhist philosophy, but also with present day science. According to the Buddhist understanding, we cannot change existing karma, but we can change the generation of new karma and we can influence the way in which existing karma comes to fruition. The research in epigenetics comes to a parallel conclusion: "In the nucleus of eukaryotic cells, genomic DNA is highly folded and compacted with histone and non-histone proteins into a dynamic polymer called chromatin. Gene expression, chromosome segregation, DNA replication, repair, and recombination all act, not on DNA alone, but on this chromatin template. The discovery that enzymes can (re)organise chromatin into accessible and inaccessible configurations revealed epigenetic mechanisms that considerably extend the information potential of the genetic code. Thus, one genome can generate many 'epigenomes', as the fertilised egg progresses through development and translates its information into a multitude of cell fates. [...] This suggests that "We are more than just the sum of our genes", and that biological complexity depends less on gene number, and more on how those genes are used (expressed), which is largely due to epigenetic mechanisms."
In simple terms: our fate is not (necessarily) encoded in our DNA.
There is a wonderful little documentary Nova Science Now that introduces epigentics in a very accessible way: http://www.pbs.org/wgbh/nova/sciencenow/3411/02.html