French twins Thomas and Vincent (L) Seris take the tram in Bordeaux, November 12, 2014. Born with Xeroderma Pigmentosum (XP), the twins cannot be exposed to the sun and its ultraviolet (UV) light, which could provoke precocious cancers due to an autosomal recessive genetic disorder of DNA repair. Colloquially referred to as Children of the Night (Les Enfants de la Lune) the Seris twins are among 70 to 80 people in France who suffer from the genetic defect. The French association “Les Enfants de la Lune” reports that there are between five and ten thousand such cases in the world. Thomas and Vincent have been testing a new protective mask for the last year which is transparent and ventilated and developed by several hospitals in France. (Photo by Regis Duvignau/Reuters)

French twins Thomas and Vincent (L) Seris pose in Bordeaux, November 12, 2014. (Photo by Regis Duvignau/Reuters)

French twins Thomas and Vincent (R) Seris are reflected on a car window as the walk in the street in Bordeaux, November 12, 2014. (Photo by Regis Duvignau/Reuters)

French twin Vincent Seris (L) uses a device to check for ultra violet light in Bordeaux, December 12, 2014. (Photo by Regis Duvignau/Reuters)

French twin Vincent Seris holds a device which is used to check for ultra violet light in Bordeaux, November 12, 2014. (Photo by Regis Duvignau/Reuters)

French twins Thomas and Vincent (L) Seris pose in the street in Bordeaux, December 12, 2014. (Photo by Regis Duvignau/Reuters)

French twin Thomas Seris holds his protective head gear as he walks in the street in Bordeaux, December 12, 2014. (Photo by Regis Duvignau/Reuters)

French twns Vincent (R) and Thomas Seris buy fruits while shopping in a commercial centre in Bordeaux, November 12, 2014. (Photo by Regis Duvignau/Reuters)

French twin Vincent Seris (R) pushes a caddy through the aisle while shopping with his brother Thomas in a commercial centre in Bordeaux, November 12, 2014. (Photo by Regis Duvignau/Reuters)

French twins Thomas and Vincent (R) Seris walk in the street in Bordeaux, November 12, 2014. (Photo by Regis Duvignau/Reuters)

French twins Thomas and Vincent (L) Seris take the tram in Bordeaux, November 12, 2014. (Photo by Regis Duvignau/Reuters)

French twins Vincent (R) and Thomas Seris wait for the tram in Bordeaux, November 12, 2014. (Photo by Regis Duvignau/Reuters)

French twins Vincent and Thomas (L) Seris speak with a student at the university in Bordeaux, November 12, 2014. (Photo by Regis Duvignau/Reuters)

French twins Vincent (L) and Thomas Seris wait for a tram in Bordeaux, November 12, 2014. (Photo by Regis Duvignau/Reuters)

French twins Thomas and Vincent (R) Seris walk in the street in Bordeaux, November 12, 2014. (Photo by Regis Duvignau/Reuters)

The new transparent and ventilated protective mask worn by French twins Vincent and Thomas Seris are pictured in Bordeaux, November 12, 2014. (Photo by Regis Duvignau/Reuters)

French twins Thomas and Vincent (L) Seris pose in Bordeaux, November 12, 2014. (Photo by Regis Duvignau/Reuters)

French twins Vincent (R) and Thomas Seris leave their apartment in Bordeaux, November 12, 2014. (Photo by Regis Duvignau/Reuters)

French twins Thomas and Vincent (L) Seris pose in the street in Bordeaux, December 12, 2014. (Photo by Regis Duvignau/Reuters)