The name of the science, epigenetics, puts genetics in its place. Genetics is the study of genes, the so-called basic units of heredity encoded in specific sequences of DNA nucleotides.  Epigenetics means the study of those things over and above the gene (“epi” is a Greek prefix that means “above” or “over”).

For too long, scientists have assumed that there isn’t anything “above” the gene.  That is, anything that appeared to be above the gene—the cell, and more importantly, the larger multi-celled organism and everything it is, does, and ever will do—they declared to be reducible to the gene.

Hence, the wild fervor in, and jubilation about, the Human Genome Project.  If we map the entire genome—the entire genetic sequence—then human nature will be an open book. Having cracked the code, we’ll be able to read our form and fate.

Such was the doctrine of necessity, but “it ain’t necessarily so.” According to science writer Ethan Watters, the recent work of epigeneticists “has made it increasingly clear that for all the popular attention devoted to genome-sequencing projects, the epigenome is just as critical as DNA to the healthy development of organisms.”

Proof? Here’s an interesting example. We’ve been led to think that every malady we suffer—say, obesity, or proneness to diabetes or cancer—is caused by our having an unlucky gene. And even worse, we’ll pass this unlucky gene to our offspring, and they will do the same in turn.

Enter a neat little experiment with Agouti Mice, so named because they carry a particular gene, mellifluously called the agouti gene, that not only disposes them to being overweight but also to contract diabetes and cancer. A sure case of DNA is destiny.

Not so. Instead of trying to micromanage the genome, researchers did the motherly thing, and changed the mouse’s diet. Whereas before, most of the offspring of such mice were doomed to display the same traits, now, after a diet change, the majority of the offspring produced were perfectly healthy mice.

DNA is not destiny. The “diet rich in methyl donors,” a type of molecule found in many ordinary foods, such as onions, garlic, and beets, turned off the agouti gene in the offspring.  The lesson: there is a big difference between having a gene, and having that gene expressed.

But things are stranger still. Let’s turn from mice to rats. As with human mothers, so also with mother rats: some are very motherly, others are cold and distant.  Researchers found that affectionate mother rats actually had a positive effect on their offspring after they were born.

The nurturing activity (licking their young) actually caused the hippocampus in the brain of offspring to develop more fully and to release less of a particular stress hormone, cortisol. The result: calmer, less skittish rats. The rats with cold and distant mothers, by contrast, were nervous and timid, and developed smaller hippocampi.

Why? The mother’s motherly licking released serotonin in her little pups’ brains, which nudges the hippocampus to send a protein message to turn on genes that inhibit stress.  A little motherly love, and DNA is no longer destiny.

From mice (and rats) to men? What does it mean?

To begin with, this crack in reductionism cannot help but become bigger and bigger. If mere diet changes and a little motherly love can have such dramatic effects, what else might change our DNA expression from a pre-written script, to a story we help write, both for ourselves and our offspring?

Epigenetics therefore represents a major shift…back to common sense. Predestinarian DNA-ism denies the common sense notion that what we choose to do and not to do has a real effect on our lives and the lives of others. But if such small changes makes such large differences in mice and rats, what we human beings choose to do and not to do could make a world of difference. Free will is not only real; to a yet undetermined extent, it can override DNA.

But these latest scientific discoveries also spell the end of the reductionist paradigm of neo-Darwinism. As with Darwinism, neo-Darwinism wanted to keep everything simple. The chant that DNA is destiny was a way to make life, including human life, so simple that it needed no other explanation than that provided by brute materialism.

Neo-Darwinians therefore claimed that they could explain all of human life in all its complexity in terms of genes—bodies, minds, romance, art, literature, passions, pursuits, politics, religion, music. All could be put down to which genes won out in the struggle for survival, and some occasional happy mutations.

Now it seems like the reverse. The greatest effect on our genes might be epigenetic.  Beautiful music, deep romance, and great art could yield just as significantly beneficial results as motherly and fatherly affection. Suddenly, epigenetically caused gene expression is as much if not more important than the genes themselves.

This presents a serious difficulty to neo-Darwinism. The charm of neo-Darwinism was that it was simplicity itself.  All complexity could be explained by a simple, one-way mechanism. Beneficial genes caused beneficial traits; natural selection picked off the less fit; those with more beneficial traits survived to hand on their genes.

But epigenetics opens up the possibility that there are literally countless things above the level of the gene that could contribute to something’s ability to survive, be it mouse or man. That is not simplicity itself, for the genes only tell half the story. The other half is epigenetic.