A recent study has shown that as a man ages, his sperm becomes poorer quality, which can cause a number of diseases like autism or schizophrenia in his children, Daily Mail reports. This study was performed by Decode Genetics, a leading genetic research company.

For a long time scientists had thought that only the age of the mother was important -- the older the mother, the bigger the risk of pathologies in the child. Now new studies published in the respected journal Nature show that the father’s age is important, too, and a man in his 40s is twice as likely to pass on a number of potentially disease-forming genetic mutations to his child as a man in his 20s.

Researchers analyzed the DNA of 78 Icelandic parents and their children and found out that there was direct link between the father's age and the number of mutations linked to autism spectrum disorders and schizophrenia in a child's DNA. Meanwhile, the mother’s age played no big role at all – at least, according to the research, 97 percent of all mutations in a child's DNA come from the fathers.

“Society has traditionally been very focused on the age of the mother, but it seems that disorders such as schizophrenia and autism are actually influenced by the age of the father and not the mother,” says Dr. Kari Stefansson from of Decode Genetics.