This story has been making most of the news programs today.
Concern about advancing maternal age is well-documented. Now, a recent study led by Dr. John McGrath of the Queensland Centre for Mental Health Research undertaken in conjunction with US researchers has shown a link between advancing paternal age and reduced IQ in children.
Test results from more than 33,000 children in the US were analysed and revealed subtle impairments associated with delayed fatherhood. These impairments were still significant even after adjusting for socioeconomic differences and the mother's age. While the study doesn't suggest a cause, Professor McGrath suggests such differences may result in more DNA errors contained in the sperm of older fathers.
Note I bolded the word subtle above. Professor McGrath advises against alarm.
The effect we see is very small. There are many, many more
important things to worry about with respect to childhood
IQ, like maternal diet, the child's diet, educational opportunities,
a stable family life, maternal smoking, maternal drinking,"
To read the study in full, please click here.