Children of stressed fathers are at greater risk of developing PTSD and depression, according to a new study.
Researchers found life's pressures can change the DNA of a man's sperm - leading to brain development changes in his yet unborn baby, the Daily Mail reports.
It's widely known that a mother's environment during pregnancy, including factors such as poor diet, stress and infection, can negatively impact the offspring.
Learning how a father's behaviour and environment can impact his child's development could lead to the detection and prevention of many mental health disorders.
"Researchers have known for years that stress can increase the risk of mental disorders," Dr Tracy Bale, professor of neuroscience at the University of Maryland School of Medicine, told Daily Mail Online. "What's interesting here is that we are finding intergenerational effects."
Researchers, led by Dr Bale, conducted a mice experiment to examine how a father's lifestyle impacts his children.
Previously, the team has found male mice experiencing chronic periods of mild stress passed down genetic coding for a less effective hormonal response to stress in children.
Three major hormones are released by the nervous system when the body is under stress. These are adrenaline, cortisol and norepinephrine. Collectively, these hormones send our bodies into 'fight or flight' mode, which is important to the body's ability to cope with the effects of stress.
Stress resulted in changes in sperms genetic material known as microRNA, which plays a key role in which genes become functional proteins.
These changes in stress reactivity have been linked to some mental disorders, including depression and PTSD.
In the new study, presented at the 2018 AAAS annual meeting in Austin, Texas, Dr Bale and her colleagues unravelled new details about the microRNA changes in the sperm.
The caput epididymis, the structure where sperm matures, release vesicles which contain microRNA that can fuse with sperm to change its cargo delivered to the egg.
When males mice were stressed, the caput epididymis responded by altering the content of these vesicles.
This suggests even mild environmental stress, such as workplace stress, can have a significant impact on the development and potentially the health of future offspring.
This is through a process known as epigenetics where DNA is changed through lifestyle factors such as diet, exercise - or even stress.
Scientists have known a mother's environment during pregnancy can damage a fetus by diet, stress or infection affecting the expression of certain genes in the same way.
But Dr Bale and colleagues have shown a father's stress can also affect offspring development - by altering important aspects of his sperm.
Her previous studies on the placenta have revealed novel sex differences during pregnancy that may predict increased pre-natal risk for neurodevelopmental disorders in males.
Historically, most research on how a parent's lifestyle, behaviour and environment can affect their children has focused on the mother.
But scientists have recently been paying increasing attention to how a father's health impacts his children.