Board Thread:Theories and Rumors/@comment-32364859-20170710050027/@comment-30499831-20170712220136

Extinction17 wrote: Remember, Garmadon was banished to the Underworld forty years before the pilot episodes. Then, it was revealed he had a son before his banishment but that son only appears in the form of an eight-year old boy. This would be very confusing, if you forgot how the family of Spinjitzu Masters age. For me, it's already figured out: Lloyd was born forty years ago, but because he's from that family, it was in his genes to age slowly so it didn't matter. No, he was banished a decade before. Don't be fooled by Garmadon and Wu's looks. 30 years passed between those events. Ray and Maya looked the same when they were kidnapped, but Kai and Nya are obviously not over 40 years old.

Serpentine War: 40 years ago

Garmadon's banishment/Ray and Maya's kidnapping: 10+ years ago