The difference between "these" and "those," or between "this" and "that," is not related to whether something is the real thing or just a representation. Anyone who sees a photograph in the 21st century will know that it represents people, but it is not the people themselves. It is about nearness versus distance.
If you are holding the photograph and showing it to the other person, use "these are my parents."
If the other person is holding the photograph and you are explaining who the people in it are, use "those are my parents."
