Forbidden love

As a German couple attempt to change the country's law banning incest, a human genetics expert argues incest should remain illegal. The German media have identified the siblings as 30-year-old Patrick S., and almost 23-year-old Susan K., who have four children together. The pair first met in 2000, as they grew up separately, spending time with foster parents. But Juergen Kunze, human genetics professor at Berlin's Charite university hospital, argues incest should remain against the law. Joanna Partridge reports.