Realistic/Ambiguous Portraits

 This picture looks real because the subject is looking out of frame instead of at the photographer.

 This picture looks natural because the girls is facing away and the swing is in motion.

 This picture looks real because of how relaxed and natural the subjects are.

 This picture looks unposed because it is capure in a moment that seems spontaneous.

This small child is building with blocks. That is what children do. Hence, natural picture.

These pictures both turned out well, though there are bits of background in each that are distracting and could be darker. They look real because of the natural positions of the subjects and the fat that they are looking at each other, not the camera.