Smoking is one of the most powerful negative lifestyle factors that affects not only the whole organism, but also the activity of genes, “turning on” and “turning off” entire clusters of different genes. Epigenetic modifications can cause the development of many diseases (the most obvious are oncological and cardiovascular). Every year there are more and more studies about how smoking affects the epigenetic state of human DNA. An international team of experts conducted a meta-analysis of 16 papers covering data from about 16,000 people, including smokers, people who had given up a bad habit, and those who had never smoked. It turned out that smoking changes the activity of more than 7,000 genes — a third of all the genes that make up our genome. If a person has quit smoking, then most of these changes disappear within five years — they return to their original “smoking-free” appearance. But there are also areas in the DNA that, even many years after a cigarette is finally smoked, remain with a “nicotine” label. Such marks occur, among other things, in germ cells (in the mother’s eggs and the father’s spermatozoa), so they can remain in the next generations — children and grandchildren can literally feel the bad habit of their parents. Hormones, a mother’s nutrients, and her psychological state can change the way her child’s genes work. The same thing happens with fathers: lifestyle, in particular adherence to bad habits, can affect how the molecules that “conduct” the genes of his children function. And first of all, it is the “paternal” marks that affect the child’s development, according to scientists from Georgetown University (USA). Numerous studies prove this. For example, specialists from Florida State University and Massachusetts General Hospital (USA) The following experiment was conducted with laboratory mice: for 12 weeks, nicotine was added to water for males, and then they watched how this would affect their offspring in two generations. The children and grandchildren of the “smoking” mice performed worse on cognitive tests than the offspring of the “non-smokers”, they suffered from hyperactivity disorder, and their brains had significantly fewer neurotransmitters — biologically active substances with which nerve cells transmit electrochemical impulses to each other. The analysis showed that nicotine triggered an epigenetic switch so that negative changes occurred in the sperm DNA of mice, in particular in one gene associated with brain development. This harmful habit is even more dangerous if parents start smoking at a very early age. Dr. Marcus Pembrey from the University of Bristol (UK) and his team analyzed data from almost 10,000 men and their children and found that if fathers started smoking before the age of 11, their sons were on average fatter than the children of fathers who started smoking later. And the earlier they became hostages of smoking, the higher their sons’ body weight was. Of course, first of all, smokers harm themselves (according to the data According to the World Health Organization, more than eight million people die from the effects of smoking every year — tobacco users, former smokers, as well as those who have ever been exposed to secondhand smoke). However, the information received is sufficient to confirm that smoking has a negative impact on children who have not yet conceived. Maybe you should start writing on cigarette packets: “Smoking is harmful to all the children you will ever produce”?

Regular and excessive alcohol consumption can cause such changes in gene expression that, as a result, a person’s craving for alcohol will become even stronger, scientists from Rutgers University (USA) have found out. They drew attention to the activity of two key genes involved in controlling drinking behavior: the first is PER2, responsible for setting up the body’s biological clock, and the second is POMC, which regulates the stress response system. Researchers have found that regular alcohol users and binge-addicted people have decreased expression of these genes and the rate at which they produce proteins. As alcohol consumption increased, so did these changes. This means, the authors note, that people who drink a lot have a stronger craving for alcohol than others. Alcohol leads to irreversible changes in the brain, researchers from the University of Pennsylvania (USA) came to this conclusion after conducting experiments with laboratory mice. They found that acetate, a byproduct formed in the liver during the breakdown of alcohol, has the greatest effect on the enzyme ACSS2, which is a kind of “fuel” for the entire process of gene regulation, and also plays a key role in learning and memory. Because of this, experts say, drinkers and former alcoholics become very susceptible to environmental signals — triggers that can easily prompt them to drink. Therefore, “recovering” alcoholics can easily break down again — this is an epigenetic regulation in the brain. In another experiment, scientists from the University of Cambridge (UK) gave mice diluted ethyl alcohol, and then monitored the effect of acetaldehyde on animal genes (this substance is formed in the body as a result of ethanol metabolism). Analysis showed that alcohol causes irreversible changes in the DNA structure of blood stem cells (double—stranded breaks occur, DNA repair is disrupted – the function of repairing damage, chromosome rearrangement is caused), which contributes to the appearance of malignant neoplasms. Alcohol consumption increases the risk of developing at least seven types of cancer, including breast and bowel cancer.

Drug use also has its own effects on the genome. Scientists from Duke University (USA) It has been established that marijuana, namely its main psychoactive component tetrahydrocannabinol, affects gene expression and causes structural and regulatory changes in sperm DNA. At the same time, the higher the concentration of the substance, the more pronounced the genetic changes were. According to the authors of the study, this threatens to disrupt the human reproductive system. Numerous studies have also demonstrated that drug use by parents harms not only themselves, but also contributes to the development of malformations and genetically determined diseases in their children. For example, American researchers from the same university have identified a potential link between fathers’ cannabis use and the development of mental illness in their children. In men who used marijuana, they found several adverse changes in gene activity, in particular in the Discs-Large Associated Protein 2 (DLGAP2) gene, which is involved in the transmission of neural signals in the brain and is associated with autism, schizophrenia and post-traumatic stress disorder. Experiments on rats confirmed that the epigenetic changes were similar in the offspring born, which confirms the likelihood of passing on the “marijuana” label from generation to generation. Another study by the aforementioned university demonstrated that the use of marijuana by the father affects the cognitive functions of the child: impairments were found in some areas of the brain associated with learning, memory, reward, and mood. Marijuana has dangerous consequences for the future generation, even if parents smoked it only in adolescence and gave up the bad habit long ago. Researchers from the University of Washington found that the children of such parents had an increased craving for not only drugs, but also alcohol: they were 2.5 times more likely to use marijuana and 1.8 times more likely to drink alcohol, compared with children whose parents had never used. Of course, it’s not just “light” drugs that are dangerous. A team of scientists from Fudan University (China) It was found that the children of fathers who used cocaine inherit drug cravings from them. Experts conducted an experiment on laboratory rats, in which they gave cocaine supplements to males, and then observed the behavior of their offspring. When the cubs grew up, they were hooked up to a cocaine “dropper” and allowed to independently press a button that injected a portion of the drug into their bodies. It turned out that the children of rats who used cocaine developed addiction faster, and their brains reacted much more strongly to the drug than other cubs. This trend continued in the next generation. Chinese scientists have recorded thousands of changes in the DNA structure that have been passed on to children and grandchildren.

The mechanism of epigenetic inheritance has only recently been discovered, and researchers have had few opportunities to trace this phenomenon across several generations of humans, which is why there are so many experiments on laboratory mice (they have a similar DNA structure) and so few on humans. And yet scientists are sure that lifestyle can affect our genes and the genes of our descendants. It is important to give up bad habits and start taking care of yourself and your health: follow a diet, be physically active, be more positive, avoid stress, and do what you love. Maybe healthy habits can also be passed on to our children?