I was sitting on a couch between the wife and the husband of an old married couple (native English Londoners) and they were showing me pictures of their kids. They kept using phrases like
here is my son during his holiday
my daughter is the first person from the right
It took me some time before I realized they had been speaking about the children they had together. In my language I would for sure have used our.
The question is:
Is it OK (or even preferable?) to use my in situations where the "co-owner" is sitting next to me, like when talking about our common kids or about a house we both own together?
There is a similar question "Our team" or "My team"? but I think it covers slightly different use case.
I am aware that English uses possessive pronouns much more often than many other languages, often just as a form of article. When you say I am wearing gloves on my hands you probably do not intend to emphasize your ownership of that pair of hands (in many languages the translation can get by without the my, it even sounds redundant).
Could it be that in the connection my son the possessive pronoun my is perceived as rather just a complement needed just for grammatical correctness of the sentence, and not the actual expression of the possession?