does this refer specifically to their 'own' milk, or is it ambiguous to if the possessive refers to the topic or another subject? Also, like how in English 'their' is singular and plural, is 'hun' specifically plural, because 'zijn' is can be for 'his, her, its' ?
My wife is Dutch and says the narrator has a really strong regional accent.
That's true, but the phrase wouldn't make sense with "hond" in place of "hun". Most of times, we've to deal with such accents (try to listen french from Marseille...)
I guess katje is also correct. Usually anything with -je means the smaller edition. :) Example: zoontje - baby son, zoon - son
I am struggling to understand when to use hun, when to use zijn and also the other one (is it hen or hem?) Is there an explanation?
When it comes to possesive pronouns: Hun means "Their" that is, belonging to them. Zijn means "His" or "Its" that is, belonging to him or belonging to it.
When it comes to object pronouns: Hem means "him" Hun/Hen means "them", however Hen seems to be the more literary form, whereas most dutch people supposedly use Hun, so it would be better to stick with that in my opinion.
Hope I helped.