Children born to older fathers are not just at an increased risk of autism and some other diseases but are also more likely to be ugly, scientists say.
Previous studies have shown that extra genetic mutations that build up in older men's genes can raise their children's risk of autism, schizophrenia and other diseases.
Now researchers suggest the impact is so strong that it also affects the appearance of those who have older fathers.
"We found a significant negative effect between paternal age and people's facial attractiveness," said Martin Fieder, an anthropologist at Vienna University and one of the research team leaders.
"The age of the father at conception is not only a determinant of the risk for certain diseases but also predicts facial attractiveness," Fieder said.
In the study, a group of six men and six women was shown photographs of 4,018 men and 4,416 women, mostly aged 18-20, and asked to rate their attractiveness, 'The Sunday Times' reported.
The researchers found that subjects with older fathers tended to be consistently rated less attractive than those with younger fathers. The study is the latest to challenge the idea that the mother's age affects a child's health and to show that, for lifelong health, paternal age is far more important.
This is because in women, eggs are created during foetal development and stored until puberty.
In men, sperm are produced throughout life. With age the sperm-producing cells lose their ability to copy a man's DNA exactly, so errors creep in and are passed on.
"Every 16 years the mutation rate doubles. Other researchers found 25 mutations per sperm in a 20-year-old, but at age 40 it is 65 mutations. By 56 it doubles again," said Fieder.
By contrast, the number of new mutations passed on by the mother was always about 15, regardless of age. "The effect is very visible - someone born to a father of 22 is already 5 per cent-10 per cent more attractive than those with a 40-year-old father and the difference grows with the age gap," Fieder said.
Fieder emphasised that his findings were statistical, so not everyone born to older fathers would be uglier, especially those born to fathers who were reasonably attractive to start with.