It's not just the arm, one sleeve is also darker than the other. It's just a very poor quality image. That same boy appears in a group photo with Mark and his two younger brothers, where once again he's named David. This image appeared in a book written by Mark, it wasn't shown at the time of our initial discussions as to the possible ID of the boy they insisted was a brother to Mark, born a few years later...Mark was born in 1965.
The reason this 'David' was implanted into the family story has to be to continue the fiction that the boy standing between the Kenyan student and Ruth is MARK, which isn't true. Ruth is holding Mark, born the year after she arrived in Kenya, and the dark boy is about five years old, which means he was born in 1961, PROBABLY IN Hawaii, He's the child Mary babysat when, in her own words, her daughter, who was born in July 1959, was 18 months of age.
Do the math. The dark boy was therefor born in January 1961. An excerpt from Mark's book:
I doubt if anyone was killed in a motor cycle accident. The dark boy grew up, and according to Malik, he and the young Barack Obama grew up together, the young Barack taught school in Uganda, and in 1982, after attending his father's funeral, he disappeared...