The main challenge in shooting candid portraits is the lack of control in general (in terms of composition, lighting, etc.) This also applies to the colours in the image – the clothes of the subjects and the background. Sometimes, the colours are so loud and clashing that the best thing to do is to ignore them during the shoot, and simply convert the image to monochrome in post-processing.
When I took photos of my mother and daughter baking together in a small kitchen, the quarters were so tight that I did not have much choice in terms of the composition. Fortunately, a 35 mm lens provides a wide enough field of view to allow some cropping afterwards. In terms of the colours, I did not want to convert the photos to black-and-white if at all possible, so I tried to position myself so that the brightly coloured background elements (e.g. a wall calendar, etc.) would not be in the frame. In this particular case, the scene itself, which has a lot of sentimental value for me, outweighs the technical shortcoming.