A US clinic is offering would-be parents the chance to select traits like height and intelligence to "genetically optimise" their future babies on top of the usual screenings for hereditary diseases.

Critics of the start-up company have questioned the ethics of this and experts in human genetics are also questioning the science behind it.

Niall talks to Sky's science and technology editor Tom Clarke about what the concerns are.

Producer: Tom Gillespie

Editor: Wendy Parker