Australians are turning 30 before buying their first home, according to new research. The Genworth International Mortgage Trends Report, released yesterday, puts the average age of first home buyers at 31. In the decade from 1970 to 1979 the average age of first home buyers was 25. In the following decade the average age rose to 26 and in the years between 1990 and 1999 it rose to 29.Commentators usually attribute this trend to the high cost of housing in Australia, the country's relatively high interest rates and cultural change that has seen the adolescent lifestyle extend into the mid-20s.Genworth's research suggests there is another factor at play. People are accumulating significant amounts of personal debt in the years before purchasing their first home, which is acting as a hurdle to taking on more debt.Among respondents to a Genworth survey who identified themselves as "potential first home buyers", around 40 per cent said they were spending 30 per cent or more of their after-tax income servicing personal debt.Almost 20 per cent said they were spending 50 per cent or more of after-tax income servicing personal debt."These people can't afford to take on more debt," said Alan Shields, research director at Retail Finance Intelligence, which conducted the research.Genworth Australia chief executive, Ellie Comerford, said there were no simple answers to the problem of affordability but lenders in other markets were more innovative with product designed that addressed the issue.Comerford said: "In India home buyers can take out an accordion loan, which has capped repayments and adjusts the term as rates change."Terms are longer in some markets. Borrowers under 30 in the UK can get 35 year terms."