Scientists have revealed that excessive smoking, drinking alcohol and cocaine or exposure to pesticides cause chemical changes in male sperm.
"If I were a young man I would not drink heavily and I would not be smoking two packs of cigarettes per day while trying to conceive a child," Telegraph quoted Dr Cynthia Daniels of Rutgers University, as saying.
Animal studies have shown that exposure to environmental toxins caused abnormalities that were passed on through generations.
"Studies have shown significant associations between male toxic exposures and increased rates of infertility, miscarriage, stillbirth and childhood health problems," she said.
"When you harm the male reproductive system you can see multi-generational harm transmitted through the male gamete [sperm]. This [new] research has human implications because it suggests an avenue of harm and a model of trans-generational effects," she added.
Dr Matthew Anway, of the University of Idaho conducted the study using a rat model where he gave pregnant female rats daily injections of the pesticide vinclozolin during the period when the sex of embryos is determined.
The researchers found that male offspring had abnormalities including prostate and sperm development problems, and genetic changes that were passed on through four generations when the males were mated with healthy females.
Dr Anway found that the genes involved in the production of sperm were permanently altered by exposure to the pesticide.
"In addition to the spermatogenic and prostate abnormalities, trans-generational effects on numerous disease states were observed including tumour development and kidney disease," he said.
The findings were presented at the American Association for the Advancement of Science (ASSS) conference in Boston.