Mothers are on the spot once again for causing their children’s psychological problems. This time it goes even further: they could affect not just their children, but their grandchildren and great-grandchildren — even without meeting them.
And guess what: one of the biggest contributors to good mothering is avoiding stress. So moms: everything you do could affect your child’s life forever, but make sure you don’t worry about it!
Two male (color me shocked) scientists are credited with founding the branch of epigenetic research responsible for these conclusions. Michael Meaney and Moshe Szyf posit that nurture — one’s experiences and environment — can alter the expression of DNA permanently. Early childhood experiences have a stronger effect than later life does.
Methyl groups and acetyl groups are the key substances involved. “Methylation [adding methyl groups to DNA] switches genes off. Acetylation [adding acetyl groups to histones, which are the proteins wrapped around DNA] switches them on.” The DNA remains the same, but it is expressed differently because different genes are off and on as a result of life experiences. Epigenetics is the study of this process. The question at hand is whether the modifications to methyl and acetyl groups can be passed down, and the answer looks like a resounding “yes.”
Don’t worry about it if you didn’t understand that paragraph (especially mothers of young children: don’t worry! Just generally!). The point is that people can inherit the chemical results of their progenitors’ experiences. Discover Magazine dubbed it “postnatal inheritance.”
Most of the experiments demonstrating these effects involved subjecting mice to bullying or neglectful parenting. The Los Angeles Biomedical Research Institute went a different route, injecting the hapless rodents with nicotine. The results showed that a smoker’s offspring could suffer diseased, asthmatic lungs even if they didn’t smoke themselves. One more reason to quit.
The good news is the evidence that methylation and acetylation can be reversed. When injected directly into rats’ brains, a drug that removes methyl groups undid the methylation that their “rotten mothers” had caused.
The Economist struck a moralistic tone after describing the nicotine study:
Epigenetics is a reminder that when making choices about what you eat and drink and put into your body, and what you do (go for that daily walk or hunker down on the couch with a bowl of something salty), you’re not only doing it for yourself, but for future generations and for the future of all of us.
Discover Magazine’s article about this area of study had similar subtext. In addition to the “rotten mothers” language quoted above, it stated that “miserable mothering” made children into “nervous wrecks,” and the damage could be seen in the second generation’s brains.
If you aren’t feeling bad enough, moms, how about being blamed for suicide? A study comparing the brains of people who committed suicide with others who died from different causes found lots of methylation in relevant parts of the suicide victims’ brains. Childhood abuse was particularly closely associated with excess methylation.
One study of paternal contributions to messed up gene expression managed to blame mothers even for dads’ shoddy genetic material. First the researchers locked male mice up with meaner mice who bullied them for days. Then they got each of the bullied mice together with a female mouse who became pregnant. The bullied father never met his kids, who came out pretty messed up emotionally.
Here’s the twist: when researchers artificially inseminated female mice with sperm from the bullied mice, so that neither mother nor babies ever met dad, the kids wound up fine. That’s why this is all mom’s fault: when she knew she had mated with a “loser,” as Discover put it, she neglected the resulting babies. I guess she figured they were doomed no matter what she did. But when she didn’t know that the sperm donor was such an undesirable, she nurtured her babies well and undid the damage dad’s genetic contribution caused. Or so goes the theory.
After hammering them, the science offers mothers two rays of light. The first is that orphans suffer more methylation than children never separated from their biological parents, so even if these studies have left you nervous, don’t give the kids away to a “better” mom. Just being with you is beneficial. The second is that one of the most effective things moms (and presumably dads) can do is touch their babies a lot. There isn’t much room to worry about whether you’re doing that right or not, so go hug the tots. Your great-grandchildren will thank you.
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