This is the VOA Special English Health Report.
Sometimes people who are first cousins get married. Two people are first cousins if their mothers are sisters, or their fathers are brothers, or one’s mother and the other’s father are brother and sister. American researchers now say it is not as dangerous as had been thought for first cousins to have children.
A new study says that first cousins are only a little more likely than others to have a child with a serious physical or mental problem, or a genetic disease. It says the chance that a child of unrelated parents will be born with a serious problem is between three and four percent.
The risk for first cousins is increased by between two and three percent, to as much as seven percent. One researcher says this means about ninety-three percent of the children of first cousins are normal.
The small increase in risk exists because people in the same family may carry the same genes that cause disease. Scientists say at least five-thousand diseases are caused by these genes. If both parents have a harmful gene, it is more likely that the gene will be passed on to their child. People who are not related share fewer genes, so their chance of passing such a sickness on to their children is lower.
A committee from the National Society of Genetic Counselors reported the results of their investigation in “The Journal of Genetic Counseling.” The group examined six major studies done between Nineteen-Sixty-Five and Two-Thousand involving thousands of births. The group began the investigation after learning that some genetic counselors gave wrong information to people who wanted to know if first cousins could safely have children.
The group said in its report that no genetic tests are needed before first cousins have a child. Their report also noted that Americans fear such marriages more than people in other parts of the world.
Marriages between first cousins are illegal in at least twenty-four American states. However, no countries in Europe have such laws. And marriages between cousins are desirable in many parts of the Middle East, Africa and Asia. The researchers say their study shows that such laws in the United States should be changed.
This VOA Special English Health Report was written by Nancy Steinbach.