Unless you purchase a family album or a small cache of family photos, it's not often you find what you see here – two sister/brother portraits taken about five years apart; I found these in an a selection offered by a seller who obviously had not realized they were the same subjects. They are British but the photographer, location and subjects are not identified.
They are turn of the century formal studio portraits. Notice how much more aware the children are of their pose and expressions in the second image.