Is parenting style the result of nature or nurture?

They say becoming a parent changes everything — and now science shows that it may even change the way your brain works.

Researchers at the University of Georgia have published a study showing that when a living being becomes a parent, there are changes in parts of the brain that deal with mating, feeding, aggression and social tolerance. The changes occur in the neuropeptides, which are proteins that neurons in the brain use to communicate.

“We tested the idea that we could predict the genetic pathways involved in parenting based on old predictions from ethologists in the 1960s and 1970s,” said Allen Moore, head of the department of genetics at the university.

The team centered its experiments on an insect, the endangered American burying beetle. Though bugs are not normally the warmest mommies and daddies, the burying beetle is unusually involved in caring for its offspring. The beetles will lovingly regurgitate food for their larvae, and provide them with underground homes free from predators.

Several decades ago, behavioral scientists speculated that a parenting state happens when genetic changes occur over time. Moore and his team set out to test this prediction by sequencing the burying beetle’s genome, then measuring the changed amount of neuropeptides in new parents. They theorized that the beetle’s post-reproductive behavioral changes were the result of changes in existing genes, and not the evolution of new genes.

“When burying beetles parents feed their babies, they are feeding others rather than themselves, and so genes that influence food-seeking behavior are likely to be involved,” said Moore.

What other species might this apply to?

Moore says the research suggests that genes that influence parenting might be the same across species, and other studies have been conducted using different animals.

For many years, it has been assumed that a parent draws its parenting style from the way it was raised in the first place. An animal with a neglectful parent, in turn, becomes a neglectful parent.  It’s part of the classic nature-versus-nurture argument.

Researchers at Harvard University challenged the nurture idea with a recent study centered on mice behavior. They found that the gene for the hormone vasopressin, which is found in most mammals, may be linked to nest-building behaviors after mice reproduce.

“This is one of the first cases in which a gene has been implicated in parental care in a mammal,” said university professor Hopi Hoekstra in an article. Hoekstra co-led the study. “In fact, it’s one of the few genes that has been implicated in the evolution of behavior in general.”

Hoekstra and her co-leader, postdoctoral researcher Andrés Bendesky, tracked the parenting behaviors of several species of mice, including the way they build nests and how often they huddle with their pups. They then gave litters of some species to parents of another species.

The researchers found that when they became parents themselves, the pups acted in a way that was typical for their species, regardless of how they were raised. Certain species that tended to have absent fathers would go on to raise their pups without male involvement. This was true even if the pup was parented by a father, suggesting that genes might influence the sexes in different ways.

While examining which individual genes changed behaviors, Bendesky gave doses of vasopressin to both male and female mice. He found that nest-building behavior dropped in both.

“What we found was there’s no measurable effect based on who raises [the pups],” Hoekstra said. “It’s all about who they are genetically.”

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