I think you are too quick. You are looking for instant answers. There aren’t any. Study the subject and try to place the images in context.
Also, the background is the same in both the color pic in #615 and the one with the 4 kids from Mark’s book. Fence & brick/stonework.
The color pic in your post #615 has parts of two other pics in the background, as if it’s part of a video of a family album; one can see the black page with the pics on it.
Given the subjects of the pics - “the Kenyan” and the kids, and the kids by themselves, at the pool party - it’s family album pix of Mark.
That pic of the kid in the U of Hawaii shirt is of a different kid altogether, than the two youngest ones. Even though the skin tone is close, the head shape and feature placement is different.