The impact of nicotine on expectant mothers has long been recognized as a risk factor for their offspring, including the development of intelligence. Concerning the fathers, this was not so obvious, but the scientists clarified the matter.

Over the past five years, geneticists have found many hints that this "wrapper" of DNA is involved in the transfer of information between generations and allows animals and plants to adapt more quickly to new environmental conditions. Problems with the "rewriting" of special marks on its surface were associated with a predisposition to suicides, bad habits and drug addiction.

Bhide and his colleagues have discovered another unusual connection between these tags, harmful habits and the lives of subsequent generations of people or animals, watching how regular use of small doses of nicotine by male rats affected the lives of their offspring and grandchildren.

In the past, biologists have already noticed that nicotine in a special way changes the structure of such marks in the oocytes of smoking mothers, making their children more susceptible to the development of attention deficit disorder and other behavioral disorders. The authors of the article decided to check whether something similar would happen if the smoker was not the mother, but the father of the child. Besides, during the study, researches revealed that the smoke of tobacco contains about 5 thousand chemical compounds, 60 of which cause impotence and erectile dysfunction, that may also affect the offsprings.

To do this, scientists have grown two groups of males, one of which drank normal water, and the other — a solution of nicotine — for about 12 weeks. His dose, according to biologists, approximately corresponded to how much of this substance enters the body of moderately smoking people every day.

After this, Bhide and his colleagues crossed these mice with females who had never used tobacco or pure nicotine and followed how their young grew and developed. After they grew up, scientists crossed them with another generation of "pure" females and made similar observations.

The results struck: despite the fact that the fathers themselves had no intellectual problems, their offspring suffered from hyperactivity, attention deficit and cognitive impairment. Children and grandchildren of "smokers" were much longer looking for a way out of the labyrinth, where scientists had landed and remembered his position much worse than their fellows from "non-smoking" couples.

When female mice from the second generation were crossed again with non-smoking animals, then their offspring had some deviations in the development of intelligence, but not so noticeable. Scientists have determined that epigenetic changes have been observed in the semen of "smoking" males, including the gene that encodes the dopamine D2 receptor — this molecule plays an important role in brain development and the learning process.