Twin brothers Dawn and Don Allen were born in the 30th century. Both children, inherited their father Barry Allen's superspeed. Although the 30th century was full of fear and hatred towards metahumans, the twins used their superspeed as superheroes. To hide their identities, they spun in circles at incredible speed, giving them the appearance of tornadoes. Together, they were known as the Tornado Twins.
Don married Meloni Thawne and fathered Bart Allen, who became known variously as Impulse, Kid Flash, and the Flash. Dawn married Jeven Ognats and gave birth to Jenni Ognats, who became the Legionnaire XS.
Meloni's father, Earth's President Thawne, worked with the Dominators in an attempt to invade Earth. Fighting alongside the Legion of Super-Heroes, The Tornado Twins gave their lives in a successful effort to stop the Dominators' invasion. A version of their deaths were depicted in Legion of Super-heroes 17.