We all know our inherited DNA shapes us, but a Milwaukee researcher says how our parents - and even our grandparents - lived could also affect our genes.
"An easy way to think about it...is all of your cells have the same DNA sequence, but obviously...a liver cell and a brain cell are very different, despite the fact that the DNA sequence is exactly the same," says Lane, Lane, who chairs the Department of Pediatrics at Children's Hospital of Wisconsin and at the Medical College of Wisconsin.
"The reason they are different is this concept of epigenetics, that your body is capable and your cells are capable of...determining what genes are expressed, and what genes are expressed determines what those cells do and how they function."
So while you have a "hardwired system" of DNA that stays the same, Lane says epigenetics determines which parts of that genome are activated and which lie dormant to respond to "minute-to-minute changes as you adjust to the world." Environmental factors like stress, diet, behavior and toxins will all trigger different gene expression.
For example, it explains why identical twins get more different as they age. Despite having identical genomes, they have unique epigenomes that change in response to how and where they live.
What's more, Lane says it's thought that these activations and de-activations can be passed down to future generations.
A good example is to look at the impact of the Dutch famine experienced at the end of WWII, in which the population ate very few calories a day. Researchers found that based on where a mother was in her pregnancy during the famine, the child would be statistically more prone to diseases in adulthood like hypertension, obesity and diabetes.
"If you were going to anticipate as a fetus, as a baby, a bad environment, you would want to program yourself to store a lots of fat, because if you do get a chance to eat, you want to keep it with you," Lane says. "Our brains depend on glucose and so you would want to make the rest of your body insulin resistant so that you have as much glucose as possible to your brain."
Essentially, the mother's epigenome passed along its reaction to the famine - even though the child never starved himself. The child then living under normal dietary circumstances would be programmed toward developing these diseases.
Lane says this evolutionary adaptation of keeping epigenomic markers wasn't a problem when humans only lived to be about 20, but becomes an issue "now that we live to 50 ,60, 70 and enjoy custard."
Lane says there's also evidence that even second generations - the grandchildren of those in a famine - can be affected. In researching a Chinese famine, it was found that such an "incredibly biologically stressful event" can affect health up to four generations later.
Epigenetics is still a relatively new field, and Lane cautions that it's very hard to sort out the markers, all the while your epigenome is changing.
But figuring out how the epigenome fully works could have great practical applications for personalized medicine.
"The epigenome, because of its complexity, is one of the aspects of biology that if we figure it out, if we use the computational power we have, there is the possibility to explain and allow for the variation and the complexity of human existence and be able to predict the risk for disease," he says.
Doctors would be able to look for the exposure factors from parents' and grandparents' lived experience to determine how to treat a patient preventatively. Or vice versa, when the risk of a medical treatment outweighs the risk of that exposure.
"It's almost a generation by generation response and that is what's so attractive to it in terms of being a physician because if you can help somebody, if you can decrease a risk by adjusting epigenetics - we know we can do that with diet - then you can affect the outcomes by an early intervention in children of those adult diseases that so plague us now in the U.S.," he says.
Click here for an informative link on epigenetics.