Children of alcoholic parents often display abnormal social behaviour. One in four become alcoholics. They tend to become unconsciously addicted to another person's dysfunctional behaviour. They deny that there is a problem of alcohol in the family. Women children of alcoholics have above average gynaecological problems and men children of alcoholics are prone to frequent surgery. Other traits of adult children of alcoholics can be unclarity what is normal behaviour, difficulty completing jobs, lying when the truth would be just as easy, judging themselves harshly, not easily having a good time, serious about themselves, finding intimate relationships hard, reacting strongly to changes over which they have little or no control, seeking approval constantly, feeling that they are different from others, either overly responsible or overly irresponsible, very loyal even when continued loyalty is uncalled for and tending to adhere to a course of action without consideration of consequences.
These behavioural and psychological features are also more pronounced characteristics of foetal alcohol effect (FAE), a condition linked with lower than average IQ, learning disabilities and physical disorders. FEA is the complex result of developmental disorders that are sustained by the foetus of an alcoholic mother. In its extreme and clinical form, it is known as Foetal Alcohol Syndrome. Such babies may be born in amniotic fluid smelling of stale wine; but it is during the first and third trimesters when the foetal brain is most at risk from alcoholic poisoning. Studies with rats also suggest that genetic defects occur in the sperm of alcoholic fathers, reducing intellectual capabilities of their offspring.
Very few women who bear FAS children continue as their mothers; many have truncated or disabled lives themselves from the effects of alcoholism, and most FAS and many FAE children are raised in adoptive settings. Daughters of alcoholic mothers are much more likely to have FAE babies than the average population, presumably partly from socialization effects of the family environment, and partly because of the reduced sense of caution and judgement caused by even mild condition FAE.
Plutarch (120 AD) observed that "one drunkard begats another", and the Babylonian Talmud warned pregnant women: "One who drinks intoxicating liquor will have ungainly children". During the "gin epidemic" from 1720--1750, when cheap drink was for the first time widely available, the British Royal College of Physician warned in a report to Parliament that parental drinking was a "cause of weak, feeble, and distempered children.
Researchers reported in 2001 that they had identified an area on human chromosome 1 that is linked with vulnerability to alcoholism as well as to emotional disorders, primarily depression. Depending on circumstances, the gene or genes may manifest themselves in either form. The study also showed that in many cases, the incidence of depression in individuals was secondary to alcoholism.
Children of alcoholics are approximately four times as likely to become alcoholics as children of non-alcoholics, even when the children of alcoholics are separated from their biological parents at birth and reared by non-alcoholic parents. Children of non-alcoholic parents have a low rate of alcoholism, even when adopted by alcoholic parents. There is a 25-50 percent lifetime risk of alcoholism among sons and brothers of severely alcoholic men. Monozygotic (identical) twins of alcoholics are at significantly higher risk of developing alcoholism than dizygotic (fraternal) twins of alcoholics.