That a male's preconception behaviors and exposure to all sorts of environmental contaminants (alcohol, drugs, medicines, chemicals at work, pesticides, etc) has effects on sperm and is linked to birth defects has been known for decades. What is new is the focus on epigenetics, or as some researchers call it: inherited paternal epigenetics. Three different paternal influences that affect the fetus and child (thus paternal experiences influence what the child inherits) are discussed in a review article: paternal age, environmental factors, and alcohol consumption.The researchers also found that environmental effects during the lifetime of a father can affect not only his immediate offspring, but also future generations.
What is epigenetics? Researchers in the study summarized it as: "Epigenetics are heritable alterations in gene expression that do not involve changes in the germline DNA sequence. It works primarily through three mechanisms: DNA methylation, histone modification, and microRNA (miRNA) expression."
Huh? This means that in epigenetics, the DNA doesn't change, but external or environmental factors switch genes on and off and affect how cells read genes. In other words, it's how the environment can alter gene expression without changing the genetic code. Epigenetic change is a regular and natural occurrence, but can also be influenced by several factors: age, the environment/lifestyle (such as diet, alcohol consumption, and chemical exposure), and disease state. For example, what you eat and how much you drink (alcohol), where you live, what chemicals you're exposed to, how you exercise, even aging – all of these can eventually cause chemical modifications around the genes that will turn those genes on or off over time. Additionally, in certain diseases such as cancer or Alzheimer’s, various genes will be switched into the opposite state, away from the normal/healthy state. From Science Daily:
A growing body of research is revealing associations between birth defects and a father's age, alcohol use and environmental factors, say researchers at Georgetown University Medical Center. They say these defects result from epigenetic alterations that can potentially affect multiple generations. The study, published in the American Journal of Stem Cells, suggest both parents contribute to the health status of their offspring -- a common sense conclusion which science is only now beginning to demonstrate, says the study's senior investigator, Joanna Kitlinska, PhD, an associate professor in biochemistry, and molecular and cellular biology.
"We know the nutritional, hormonal and psychological environment provided by the mother permanently alters organ structure, cellular response and gene expression in her offspring," she says. "But our study shows the same thing to be true with fathers -- his lifestyle, and how old he is, can be reflected in molecules that control gene function," she says. "In this way, a father can affect not only his immediate offspring, but future generations as well."
For example, a newborn can be diagnosed with fetal alcohol spectrum disorder (FASD), even though the mother has never consumed alcohol, Kitlinska says. "Up to 75 percent of children with FASD have biological fathers who are alcoholics, suggesting that preconceptual paternal alcohol consumption negatively impacts their offspring."
The report is a review of evidence, human and animal, published to date on the link between fathers and heritable epigenetic programming. Among the studies reviewed are ones that find: - Advanced age of a father is correlated with elevated rates of schizophrenia, autism, and birth defects in his children; - A limited diet during a father's pre-adolescence has been linked to reduced risk of cardiovascular death in his children and grandchildren; - Paternal obesity is linked to enlarged fat cells, changes in metabolic regulation, diabetes, obesity and development of brain cancer; - Psychosocial stress on the father is linked to defective behavioral traits in his offspring; and - Paternal alcohol use leads to decreased newborn birth weight, marked reduction in overall brain size and impaired cognitive function.