grammatical number - Should I prefer "my" or "our" when the object (a kid, a house) is "co-owned" by two people both present?

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?

Answer

Yes, as Peter Shor mentioned in a comment (that he should expand into an answer IMO) the proper pronoun to use is our.

I'm sure the people in your story are smart people, so why would they use my instead? In my opinion there are several reasons why they might use my instead of our.

• I talk about my children using pronouns more frequently when I'm not directly next to my wife. As such my slips out easily and naturally even when I'm next to my wife.


• My brings the object closer to the speaker. I think my kids are awesome so using my lets me take more credit for their good qualities. This is reflected by the distancing parents occasionally do when their kids misbehave; "Erik look what your son just did!"


• It might be a subtle sign of favoritism. If you notice that the dad always says my son and the mother always uses the son's name or our son when pointing at a picture. That would imply to me that the dad wants a closer association with the son than the mom.


• It might be something distinct to Londoners. I'm an American from rural California so I wouldn't know.