Sometimes when I see mummies in a museum I wonder what those persons might have said if they’d known that their bodies would be on display millennia later.
It is perfectly normal that archeologist study old graves. However, people would be appalled if someone were to dig up their grandmother in order to examine her jaw bone. So, at what point does it become ok?
As someone who has just got a degree in archaeology I can tell you that there isn’t a definitive answer. It’s probably also dependant in which country/culture you are wanting to excavate and what you are wanting to excavate (site vs singular grave vs entire churchyard etc). The simplest answer I’ve been told is once a person, or site, is no longer in “living memory.”
Another major factor to be considered before any excavation is the cost vs benefit of knowledge and information gained by actually digging something up. Often a lot of information can be gained from the context (surrounding landscape, depth of burial, objects that someone is buried with or in, direction or position their body may be buried etc.) in which something is buried and that in itself may be enough to determine whether digging is actually necessary. Unless of course someone really wants to do some tests on their grandmother lol.
In relation to the museum displays, nowadays museums need to jump through hoops to ensure that whoever they are putting on display are being done so as “ethically as possible.” Which I’m sure many would still argue isn’t very ethical at all, however I do believe if someone can claim/prove relation to a mummy or person on display the museum has to remove that person from the exhibition if it is causing offence to a potential “relative.” At least this was what I was told during the process of developing an exhibition which included a mummy at my university.