As I wrote in my story in the New York Times today, much of your DNA is shut down by molecules collectively known as epigenetic marks. Roughly 100 sites are notable exceptions to this rule: your mother’s copy of these stretches of DNA are silenced, while your father’s are free to make proteins and RNA–or vice versa. This imbalance, known as imprinting, is utterly fascinating, and when the imprinting system goes awry–when dad’s genes start becoming active when they shouldn’t, or when mom’s genes go quiet when they should be active–the effects can be catastrophic.
I first became familiar with gene imprinting while writing an article for the Times a couple years ago about a scientist at Harvard named David Haig, who has a theory for how it had evolved. He argues that gene imprinting is the result of an evolutionary tug of war between mothers and fathers, because mammalian parents have an evolutionary conflict of interest.
Now a couple scientists are extending this conflict theory to explain why so many imprinted genes are turning up in psychiatric disorders, ranging from autism to schizophrenia. They argue that the conflict between our parents plays out in our brains, too. This morning you can read about this provocative idea in my latest Discover column on the brain, or in this article by Benedict Carey in the Times.
These articles ought to come with a disclaimer: when we write about conflicts between parents, we are speaking metaphorically. We are actually referring to the rise and fall of different genes over millions of years, as natural selection acts on populations of thousands or millions of individuals. Just because you inherited imprinted genes from your mother or father doesn’t mean they sat down and drew up plans for using to maximize their own reproductive success (unless your father was Dr. Evil, I suppose…) Nevertheless, this new research does add an extra dimension to Philip Larkin’s ode to all miserable kids, which Larkin recites in this video (if you haven’t heard it before, just be warned that there’s some old-time Anglosaxon profanity along the way):
Originally published November 11, 2008. Copyright 2008 Carl Zimmer.