They started singing when they were kids. They had hit records in Australia when Barry was 17 and Robin & Maurice were 14.
They became international superstars in 1967 and dominated the charts with 6 consecutive # 1 songs, from "How deep is your love" in 1977 to "Love you inside out" in the summer of '79.
They also wrote and produced albums for Barbra Streisand, Kenny Rogers, Dionne Warwick & Diana Ross.
To my knowledge, The Bee Gees are the only group with a hit in 4 decades. They charted on the international charts from 1966 to Maurice's death in 2003.
Robin charted recently when he recorded a song remembering UK soldiers. He had some solo efforts in the 1980s such as "Juliet".
His last recording was "The Titanic Requiem", a music score that he wrote about the 100th anniversary of the Titanic. Robin was too ill to attend the premiere.
The brothers sold over 200 million records and the Gibb songbook is recognized all over the world. They leave a pop musical legacy second only to Lennon-McCartney.