The brain is a giant
pattern-matching machine. For someone famous like the person in this photo, many of us have seen her with different facial expressions (e.g., frowning vs. smiling) and from different angles, allowing us to recognize her in completely different photos.
However, there are people who look similar to each other, who could be biologically related or unrelated, and it's often difficult to tell them apart.
As with all pattern recognition, its accuracy improves proportional to the amount of observable/observed data. For example, that's why parents of identical twins can tell their children apart: due to subtle differences that the rest of us won't be able to detect without seeing them a lot more.