Market Harborough Building Society is offering borrowers the chance to buy a home with no deposit at all - if their parents agree to put their own home up as security. The new 'family assistance mortgage' allows first-time buyers or those purchasing a new home to borrow 100 per cent of the value of the property on the condition that the borrower's parents allow a second mortgage to be taken out on their home or any other property they might own.  Over both properties, the loan-to-value can't exceed 75 per cent, meaning it will only be available for borrowers whose parents have a lot of equity in their home.