Genetic Destiny Does Not Define You

Mice with the agouti gene sport yellow fur and boast ravenous appetites (hello obesity). To add insult to injury, they have an increased incidence of cancer, diabetes, and early death. Poor lil guys are a far cry from having won the genetic lottery. When they mate, they pop out progeny fated to become fat yellow pincushions just like their progenitors. ... or so it was thought.

In 2003, Duke University researchers put an end to the “agouti curse.” Their agouti mice bore normal, slender, and healthy mouse pups with sleek brown fur. How?! Researchers simply fed pregnant mothers food with B vitamins! This diet is rich in “methyl groups” that can attach to a gene to turn it on or off. So while the mothers still passed on the nasty gene (the DNA of the mice did not change), a dimmer switch had been added to the fetus's agouti gene, silencing its deleterious effects.

Not only is the epigenome malleable in the womb, it is also affected by the environment throughout life. Researchers at McGill University studied how maternal behavior might shape the brains of offspring. They noticed that newborn lab rats affectionately licked by their mothers grew up to be relatively calm. Whereas newborn lab rats whose mothers neglected them turned out to be skittish. Just by licking their young, the mothers caused a gene that dampens the stress response to have a greater degree of expression in their offspring. Consequently the well-licked rats had a more developed hippocampi and released less of the stress hormone cortisol when startled.

"Whoopie for the well-licked, but sucks for the skittish," you might say. Don't worry. In a subsequent experiment, scientists reversed the epigenetic signals. Acetyl groups facilitating gene expression were injected into the skittish rats' brains. Presto calm rat. Alternatively injecting methyl groups into the calm rats' brains turned them skittish. In effect, researchers reproduced the effect of good (or bad) parenting with a pharmaceutical intervention.

These discoveries bolster an emerging science called epigenetics - a heretical field challenging long-standing biological dogma. For instance, we know smoking can harm your body, but we thought that when you had a child, the genetic slate was wiped clean. Turns out a study found that "the sons of men who smoke in puberty will be at higher risk for obesity and other health problems well into adulthood." Epigenetics sheds light on these heritable changes in gene expression that occur without altering the underlying DNA. Environmental factors like our diet and lifestyle choices can trigger these changes. Goodbye genetic determinism. "Epigenetics introduces the concept of free will into our idea of genetics."

“The great hope for ongoing epigenetic research," as explained in an article by Time magazine, "is that with the flick of a biochemical switch, we could tell genes that play a role in many diseases — including cancer, schizophrenia, autism, Alzheimer's, diabetes and many others — to lie dormant. We could, at long last, have a trump card to play against Darwin."