Sometimes relationship terms are also used as terms of affection, even if there is no biological relationship. Take care when a letter, diary, or a relative refers to someone as an “aunt” or an “uncle.” The use of the term may have been done out of respect and not necessarily indicate a biological relationship.
Of course, you may gain some clues or insight by researching this person, but if you find no biological connection between the individual and your family be open to the possibility that “Grandma” wasn’t really “Grandma” after all.
Those non-biological relationships mattered to our ancestors and they should matter to us as well. They give us a fuller picture of our ancestor’s life. They can help us overcome some of those research challenges that we all face.
DNA tests can help determine if those relationships we think are not biological actually are. The thing to remember about DNA tests is that they only show us those family members who are connected by biology.