One parent who admits to feeling the commercial pressures of parenthood is Zara Hobley, aged 35.

BBC: RELATED BBC SITES

Dr Javier Corripio, a glaciologist who has studied the formations in the Andes, said Dr Hobley had come up with an "interesting hypothesis".

BBC: Ice blades threaten Europa landing

With three children between the ages of one and four, Mrs Hobley believes it is important to be able to teach them about discipline and boundaries.

BBC: RELATED BBC SITES