"We love our children."
Translation:Vi älskar våra barn.
No, sina only refers back to the subject and is only used with 3rd person (han, hon, de).
Because "children" are plural. "Vårt" is for singular t-gender words. "Våra" is for plural.
No, then it would be "Vi älskar vårt barn". Notice the difference on the possessive pronoun!
So when using sin,sitt and sinna we should look at the object if it is common, neuter or plural, why when using hans and hennes we take care about the subject's sexual gender?