It’s not all about DNA, after all.
A fascinating story on the front page of Inquirer held a lot of people enthralled last Sunday. Perhaps it has become one of the paper’s “most-read” stories to date.
I found it interesting on many levels and reminded me of a discussion my daughter and I had over dinner a few days before the story landed on the front page.
My daughter, a pre-med student, was patiently explaining to me the fascinating science of epigenetics. Epi what?
“A lot of my inherited traits came from Mama (that’s how she calls my mom, her grandmother) so I am the way I am because of a lot of the stuff she probably went through as a child, or while she was pregnant with you,” my daughter began.
My mother, and not me? She certainly had my attention.
The Genetic Science Learning Center of University of Utah says, “Epigenetic inheritance is an unconventional finding. It goes against the idea that inheritance happens only through the DNA code that passes from parent to offspring. It means that a parent’s experiences, in the form of epigenetic tags, can be passed down to future generations. As unconventional as it may be, there is little doubt that epigenetic inheritance is real. In fact, it explains some strange patterns of inheritance geneticists have been puzzling over for decades.”
New science
Time magazine did a cover story in January 2010 on this fascinating new science. A landmark research was conducted by Bygren, a Norwegian scientist, and his team on descendants of people who had lived in Overkalix, a part of Norway that had known great famine and only a few years of plenty.
The Time article said, “Bygren and other scientists amassed historical evidence suggesting that powerful environmental conditions (near-death from starvation, for instance) can somehow leave an imprint on the genetic material in eggs and sperm. These genetic imprints can short-circuit evolution and pass along new traits in a single generation.”
Even more interesting, Bygren’s study showed that in Overkalix, boys who enjoyed those rare overabundant winters—kids who went from normal eating to gluttony in a single season—produced sons and grandsons who lived shorter lives.
In a paper published in 2001 in the Dutch journal Acta Biotheoretica, Bygren showed that the grandsons of Overkalix boys who had overeaten died an average of six years earlier than the grandsons of those who had endured a poor harvest.
The science of epigenetics can be explained in the most basic terms as the study of changes in gene activity that do not involve alterations to the genetic code, but still get passed down to at least one successive generation. It is through epigenetic marks that environmental factors like diet, stress and prenatal nutrition can make an imprint on genes that are passed from one generation to the next.
Bygren’s data, with those of many other scientists working separately over the past 20 years, have given birth to a new science called epigenetics.
Impact
So, yes, there is basis to saying that the kind of childhood your grandmother (if you are female), or your grandfather (if you are a boy)—the stresses she or he encountered, the kind of environmental factors they faced and lifestyle choices they made—may have had an impact on who you are today.
The conditions in the womb expose not just one generation but two. Three generations at once are exposed to the same environmental conditions (diet, toxins, hormones, etc.). However, to provide a convincing case for epigenetic inheritance, an epigenetic change must be observed in the fourth generation.
The Time article explains that epigenetics brings both good news and bad. “We all know that you can truncate your own life if you smoke or overeat, but it’s becoming clear that those same bad behaviors can also predispose your kids—before they are even conceived—to disease and early death.”
I recall the story of a cousin who said that her ex-husband’s grandfather in the 1930s did nothing day in and day out but lie in his opium bed and smoke, what else, opium. Today, she says her ex-husband likes to hole himself up in his den and watch science-fiction DVDs all night long. Different generation, a different drug, same addiction.
Science writer David Shenk, author of “The Genius in All of Us: Why Everything You’ve Been Told About Genetics, Talent and IQ Is Wrong,” says epigenetics is helping usher in a “new paradigm” that “reveals how bankrupt the phrase ‘nature versus nurture’ really is.”
Shenk believed epigenetics is “perhaps the most important discovery in the science of heredity since the gene.”
Higher risk
In an even more recent study cited by Pembrey, Golding and Bygren (2006) conducted in the UK, it was found that the sons of men who smoked in prepuberty will be at higher risk for obesity and other health problems well into adulthood.
Childhood and puberty, after all, are critical development stages, thus, you can change your epigenetics even when you make a dumb decision at 10 years old. If you drink alcohol or, heaven forbid, take drugs, you may have made not only a medical mistake but a catastrophic genetic mistake.
I suppose the same is true when, as a child, you are exposed to highly stressful situations such as violence, famine or war.
So perhaps there is some rhyme and reason in trying to find your roots so that you can better understand your strengths and quirks that a DNA test would never be able to tell you. My daughter says that although epigenetic traits cross gender, most of the traits are passed down to the same sex.
I find comfort in knowing that my grandmother (on my mother’s side) was one of the feistiest women I ever knew. She raised 15 children and lost five in a time of war. Lola Pia lived to 91, was hale and healthy, and sharp to her dying day.
Our lives and what makes us up are as complex as the human epigenome that has yet to be mapped out. To understand yourself better, look two generations up.
Meanwhile, it pays to live healthy and make wise lifestyle choices—and to teach your child to do so, too. Because someday, your grandchildren and your great grandchildren will be thankful that you did.
E-mail the author at cathy [email protected] Follow her on Twitter @cathybabao
