New research suggests heavy drinking can alter DNA in ways that increase the desire for alcohol.
Scientists say the findings may help explain why alcohol addiction is so powerful and hard to resist.
The US team looked at two genes that play a role in the control of drinking behaviour - one which influences the body's biological clock, and the other which regulates stress responses were significantly changed, making drinkers crave alcohol even more.
"This may help explain why alcoholism is such a powerful addiction, and may one day contribute to new ways to treat alcoholism or help prevent at-risk people from becoming addicted," said Prof Dipak K Sarkar, senior author of the study and director of the endocrine programme in the Department of Animal Sciences at Rutgers University-New Brunswick.
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Around 5 percent of all deaths worldwide are attributed to the harmful effects of alcohol, according to the World Health Organization. More than 75 percent of victims are men.
A process called methylation is what changes the genes, according to the study published in journal Alcoholism: Clinical & Experimental Research.