Complex sentence: Bullock grew up in suburban Washington, DC and became a proficient bluegrass multi-instrumentalist, playing in local bars while still a teenager and adopting the nickname "Robin" as a contraction of his given names Robert Allyn.
Split into simpler sentences: Bullock grew up in suburban Washington, DC and became a proficient bluegrass multi-instrumentalist. He played in local bars as a teenager while and adopted the nickname "Robin" as a contraction of his given names Robert Allyn.