When Willie Nelson admonished mamas everywhere to not let their babies grow up to be cowboys, he had no idea how accurate his assessment of a mother's power really was. Turns out, moms have a lot of control over what their babies become, both before and after birth.

To be a mom (sorry, guys)

Using Your Dinner
For instance, research done at Duke University Medical Center in 2003 revealed that what a mother eats before and during pregnancy can actually switch certain genes on and off in her child. The study took a group of obese, yellow mice and fed them diets that were rich in the nutrients vitamin B12, folic acid, betaine and choline. Despite still carrying their mother's genes for yellow fur and obesity, the baby mice born from this test were brown and remained svelte throughout their lives. This works because the gene that controls both coat color and appetite is affected by a chemical molecule called methyl groups, of which vitamin B12, folic acid, betaine, and choline are chock full. Methyl groups can switch genes on or off or, in some cases, just increase or decrease their impact.

epimice.jpgUnfortunately, while this might be a great thing sometimes, like say if it cut out the gene that might give your kid diabetes or schizophrenia, methyl groups might also turn off "good" genes, like ones that inhibit tumor growth. Right now, nobody really has a good enough idea of how methyl groups work to know how to target in on specific "bad" genes without impacting good ones. We do, however, have plenty of evidence that what pregnant moms eat affects gene expression and can have surprising consequences a long way into their children's lives. For instance, according to an October 2003 New York Times article on the subject, famines that struck Holland after World War II left many fetuses (and their mothers) malnourished. Years later, Holland saw a big increase in the number of adults with schizophrenia, an increase directly linked to what nutrients those adults had (or, rather, hadn't) gotten in the womb.

Using Your Love
Just because you've exited the womb doesn't mean your mother stops having power over your DNA expression. Research done by neurobiologists at Columbia University and Canada's McGill University has shown that maternal behavior after birth can also lead to a child's genes being turned on and off—in this case, genes that will eventually determine how that child parents their own offspring. According to a May 2006 Discover magazine article, neurobiologists studied two groups of rats, those that spent a lot of time grooming and licking their babies and those that didn't. It turned out that, if a female baby rat didn't get licked enough then her body turned off a series of genes that should have produced certain "mothering" and "love" hormones, like estrogen and oxytocin. Deprived of those, the female rat grew up to exhibit the exact same insufficiently nurturing behavior her mother had shown her—thus continuing on the cycle for another generation. On the other hand, when a baby girl rat got an extraordinary amount of lick-based attention from her mommy, she went on to actually have higher-than-average levels of estrogen and oxytocin. Again, the expression of genes and the production of hormones caused her to display maternal behaviors that were similar to her own mother's.