translate English to French: Meanwhile, his twin brother, Jean, had emigrated to the United States where he had become a chemistry professor, and with his wife Jeanette made another ascent into the stratosphere. Jean's son, Donald, continued the aeronautic tradition by pioneering the revival of hot-air ballooning in the 1960s.
Entre temps, son frère jumeau, Jean, qui a émigré aux Etats-Unis comme professeur de chimie, y a effectué, avec son épouse Jeannette, une autre ascension stratosphérique.