On Mark's website, he claimed to be the dark boy, and the lighter boy on the left was 'David'
In fact, the boy on the left is zero, over and over again, and that makes the dark boy OLDER.
Mark was born in 1965, so that doesn't work. The question that needs to be asked, is who is that boy, who was at least five years old, standing with the kenyan and Ruth and the toddler Mark whom Ruth is holding. Mark was born in 1965.
Figure that out, and you don't need any 'David' - you must remember, Ruth said at an interview that there were so many children and relatives living in that house in Nairobi, she didn't know half their names, and used to fall over them at night in the passage.
As for the images in the book to which you refer, you will have to post the images with your question. And remember, the existence of 'David' was introduced in 'Dreams' when a stranger supposedly, as he was being introduced by Auma to zero, commented, you look so much like David...
And Auma had to explain, no, it's not him, he died in a motor cycle accident.
You believe that? ...or is it possible they just had one boy too many...one Mary babysat in January, and one that Stanley Ann Dunham showed Susan in Summer?
And there they are, sitting next to each other: