Ahh, colour. And especially colour contrasts, I just love images that display this trait.
This was shot with my Canon 24-105mm f4 L zoom, and from the meta data I see it was set at 60mm focal length, and shot at f11. These are hardly the right conditions for selective focus. Never mind, as a couple of tricks can give an equally separating effect without resorting to fake bokeh tools.
I have selected the kids, inverted the selection, and applied a softening and colour loss to that area, that, in my mind at least, makes this image jump off the page and the screen. A severe crop adds to the intensity, by removing just about everything except what I am interested in seeing.