Meet Lucky Lyle and Trouble Tim. Now you might think they look a lot alike. That's because they're identical twins. But imagine them being raised in completely different environments.
As adults, they turn out very differently. Lucky Lyle is a model citizen. He goes to work, pays his taxes, treats others well, and gets an education. Trouble Tim is on a different path. He robs banks, doesn't pay taxes, and gets his first prison sentence at the same time as Lyle gets his diploma.
Their genes are identical, so it must be their separate environments that have made them so different, right? Well, there's more to it than that. Much more. We need to rewind a bit in time.
You see, one of the great questions of humanity is, what makes us us? Huh. Early explanations had a hint of the supernatural about them. As the centuries whizzed by, science emerged and fought a tough battle to gain credibility. Eventually, social science emerged with the popular theory that our environment is what makes us us.
Let's call this nurture. Undaunted, the biological sciences presented another theory. Genes. An unchangeable blueprint in you from birth decides everything. Let's call this one nature.
So, are we a product of our genes? or of our environment. The battle raged on.
Observations in a newer field of study suggest that both are partly right. This field is called epigenetics. It means above genetics and has to do with how nature and nurture interact.
At the heart of this discussion is one simple question asked by researcher Michael Meaney. What makes a good rat mama? Well, for a rat mother, nothing says love and care like some nice, vigorous licking. The higher the number of licks, the more love and the better the mama.
With this in mind, the researchers compared two groups of rat mothers, one that licked their babies a lot and another that didn't. They found that when babies grew up, they carried their mama's behavior with them and passed it on to the next generation and the next one and so on. But could it simply be that this particular group of rats was genetically predisposed to produce caring mothers?
Well, to test this, the researchers took newborn babies from low-licking mothers and fostered them with high-licking mothers and vice versa. It turns out that if the mother is a high licker, the rat baby becomes a high licker too. Regardless of whether it's genetically related to her or not.
So genes really don't have anything to do with it then? In true scientific fashion, the researchers dove right into the brains of these rats to see what, if anything, was different in the brains of the babies of high-licking versus low-licking mothers. When they looked at genes that possibly play a role in motherly care, they found crucial differences. Newborn rat babies have clusters of molecules called methyl groups attached to these genes.
These methyl groups silenced a gene, effectively switching it off. The researchers discovered that while the methyl groups in rats from low-licking mothers were still attached, in the rats from high-licking mothers, these methyl groups had disappeared. This was also true for the rats that had been adopted by high-licking rat mothers.
The care these rats received from their mothers actually physically altered their genetic expression. Now that's all fine and good for rats, but what about people? Well, the same is true for Lucky Lyle and Trouble Tim. And for you and me. The genes you're born with are the genes you've got.
But lifestyle and environmental influences such as nutrition, exercise, smoking, stress, and love greatly affect your biology. These changes can actually be observed at the DNA level. The bright side is that epigenetic changes happen throughout our lives and our choices can make real differences in how we develop as human beings.