Our health is not only forged over our personal choices. It is also rooted in the environment, the habits and sometimes the negligence of the generations that precede us. If the genetic heritage remains at the heart of medical concerns, another form of transmission intrigues the researchers more and more. Passive smoking, long relegated to a simple punctual risk factor, could actually leave much deeper imprints, before birth.
The University of Melbourne team studied more than 8,500 children followed for half a century. The investigation, named Tasmanian Longitudinal Health Study, started in 1961. Parents had transmitted their respiratory history from the launch. Having become adults, the children then carried out several respiratory tests, until the age of 53. At the same time, their fathers informed their own exposure to tobacco during childhood.
This exceptionally long follow -up, relayed by The Independent, made it possible to reconstruct an invisible thread. That of prepubère paternal passive smoking and its respiratory repercussions among descendants. The study highlighted a significant increase in pulmonary disorders in the children of these men, even if they themselves did not smoke in adulthood.
Passive smoking during childhood permanently modifies pulmonary trajectories
The detailed analysis of the data reveals a disturbing phenomenon. Children whose fathers had been exposed to tobacco smoke before puberty had a more than 50% higher risk of having an expiratory volume lower than the average throughout their lives. This measure, called FEV1, is a key indicator to assess pulmonary capacity and detection of chronic diseases such as chronic obstructive, or COPD bronchopneumopathy.
In these same families, there is also a rapid decline in the FEV1/FVC ratio, another key parameter of the pulmonary function. In other words, the children of fathers exposed to smoke in their youth see their respiratory capacity decline earlier and faster than the average. This alteration is accentuated if these children were themselves exposed to passive smoking in their own childhood.
According to the study published in the journal Thorax, these results retain their validity even after adjusting on many confusion factors, such as the asthma of the father, age, or family respiratory history. They confirm that a smoky environment during childhood does not stop at the rib cage of the one who breathes, but is part of an invisible hereditary trajectory.
Epigenetic mechanisms that change our heritage design
The researchers are advancing a hypothesis to explain these silent transmissions. That of a biological memory transmitted by reproductive cells. When a boy is exposed to smoke before puberty, when his germ cells develop, certain DNA regulation mechanisms could be modified. These so-called epigenetic changes do not change the genetic code in itself, but influence its expression.
This phenomenon has already been observed in other contexts. A recent review published by Spandidos Publications recalls that tobacco acts as a powerful modifier of DNA methylation, especially in germ cells, and that these brands can last beyond a generation. Certain studies have even established a link between the smoking of grandparents and respiratory disorders in grandchildren, even if the intermediate generation did not smoke.
In this case, the impact is not limited to temporary anomalies. This is a lasting alteration of the pulmonary function, detected in adults 53 years old. The most disturbing is that this fragility is partially independent of the subsequent smoking behavior of the father or the child. Even without ever smoking, some children inherit a weakened respiratory function, simply because their father grew up in a smoky environment.
These discoveries recall that our health choices are not limited to our own life. They are part of a biological chain, sometimes silent, always powerful. Understanding these mechanisms is giving weight to prevention, long before birth, sometimes even before design.
