One in three children, claim many tabloids, may not be biologically related to the man they call Dad. Could this really be true? This program conducts the first ever purpose-designed paternity poll, asking some truly awkward questions. Comparing rates of paternity uncertainty in Australia and the United States, we ask what is the real rate of ‘non-paternity’, and might there be biological survival benefits for children born outside marriage? Following parents and children as they seek to uncover the truth, we discover how, today, there’s nowhere to hide your genes.