Bully

Bullying is common.

I knew bully guys existed. I had heard about their dirty tricks from my school peers, I had to run away from them in the playground when I was young - if only I could know how to kill them when they bullied my younger sister.

It just happen. Everywhere. School peers, siblings, athletic coaches, doctors and even consultants. I've met them all. And yes, that's terrible.

Will bullying shape our health? Yes, even in monozygotic identical twins, according to a large study of these pairs who have, by definition, the same DNA.

To prove that upbringing and victim experience by bullying make a difference, the researchers identified 28 pairs of twins from the age of five. These twins were not easy to find. Some of them were separated into different classrooms, and the recruited twin pairs had to have one of them being bullied whereas the co-twin never experienced bullying victimization. In other words, they shared the same DNA but the bullying experience diverged.

The researchers invited these twins into the laboratory at the age of 12, and tested each child's buccal cells' DNA for methylation. They also collected each twin’s saliva to measure the cortisol level when subjected to situational testing. The test included public speaking and mental arithmetic competition; they were told they were in competition against their co-twin in order to get a prize.

How did the twins’ results compare?

It turned out that these genetically identical twins had surprisingly different results. Those who had a history of being bullied had a much higher DNA methylation and much lower cortisol response. Presumably, the bullied kids were surviving through an adaptive epigenetic mechanism. That means the kids tune down a serotonin transporter gene called SERT by more DNA methylation, and thus less protein that can be made to move the neurotransmitter serotonin into neurons. The more SERT gene is turned off, the more blunted the cortisol response.

Cortisol is a stress hormone that will surge during crisis. High levels of cortisol, in turn, can throw our immune system - something that keep us from bacteria and virus - out of whack.

Doesn't it make sense? The twin being bullied day after day would then cope better by avoiding the stress hormone storm.

If you take a deep breath and a step back, I think you'll agree with me that, in a way, the bullied twins learned their survival skill in a hard way but successfully. The rest of us have learned likewise.

Now, you might think that adding bullying to the equation would result in a tough and resilient kid. If only life were so simple. Before you pray for similar bullying exposure for your children to turn off the cortisol response, just a quick reminder that blunted cortisol response in long run can cause serious problems such as depression, and this can pass from one generation to the next.