The toys children play with have an impact not only on how they see themselves and on what skills they learn, but also on how their brains physically develop.

Some psychologists argue that this helps to explain why certain professions are so male-dominated. An increasing number of parents and carers now say they try to avoid gender-stereotyped play.

As this experiment shows, though, it’s not always easy to overcome your own prejudices.

Viewers in the UK can watch 'No More Boys and Girls: Can Our Kids Go Gender Free?' on Wednesday 16 August at 21:00 BST on BBC Two and afterwards on BBC iPlayer.