Cousin marriage not that bad: expert

A research leader in the Centre for Comparative Genomics at Murdoch University, Prof Bittles has carried out comprehensive research in countries where cousin marriage is extremely common.

"Cousin marriage is popular in North Africa, the Middle East, Turkey, South India and Pakistan," Mt Bittles said.

"In Pakistan between 50 and 60 per cent of people are first or second cousins," he said. "I've studied data sets of up to five million people so it's not as if we're stabbing in the dark here."

Prof Bittles became interested in studying this topic when he went to Bangalore for a research fellowship and discovered many people were married to their nieces.

"I just about fell through the floor I was so shocked," he said. I did a study over 10 years and we found that over 20 per cent of marriages in Bangalore in the '80s were between uncles and their nieces.

"More than 20 years later and Bangalore is now the IT capital of world so it can't be all that harmful if you've got a highly successful society."

Prof Bittles said the stigma around cousin marriage began in the mid-19th century and has continued.

"Gradually over the last 15 years it's been accepted within the medical genetics community that the ill effects of cousin marriage have been overstated in the past," he said.

"When you account for non-genetic variables like whether you're educated or whether the mother is too young or too old then you find the estimates of the harm associated with first and second cousin marriage will decline and decline."

The high percentage of people in Perth born overseas makes it difficult to pinpoint how many but Prof Bittles said there was a chance there was a number of people married to their cousins.

Prof Bittles said he wasn't trying to persuade anyone to marry their cousins but the comprehensive research needed to be recognised.

He will give a talk "Why not marry your cousins, millions do?" for the Perth Probus Club at Lake Karrinyup Country Club on September 8.