Original: Worf was then adopted by a human couple, Sergey and Helena Rozhenko, who raised him on a small farm colony on the planet Gault, a world of about 20,000 inhabitants, almost all of them humans.
Simplified: Worf was then adopted by a human couple, Sergey and Helena Rozhenko while his brother was raised in the Klingon homeworld and was not revealed until they were both adults.