Why do we say "Mag dein Kind Tiere?" and not "Mag deines Kind Tiere?" since dein is acting like a possessive adjective?
kein-, mein-, dein-, sein-, ihr-, unser-, euer-, ihr-, and Ihr- get their endings from "ein" Whenever "ein gets an ending, "dein" gets the same. Mag ein Kind Tiere? (no ending) >> dein etc. don't have an ending either. "Eine Frau ist ausgerutscht (es gab Glatteis) >> Meine Frau ist ausgerutscht.
I got it. As for calling them possessive adjectives, I was using the English nomenclature: possessive adjectivesmy, your, his, her etc; possessive pronounsmine, yours, his, hers etc. I really do not know if the same nomenclature applies to German. But thanks a lot anyway.
You are right, I am not sure about the English nomenclature and am too lazy to look it up. In Dutch we call them possessive pronouns. Anyway, calling them adjectives in English might put you on the wrong foot in German. "Mein altes Auto" has only one adjective: "altes". that is important, because the ending of "altes" is conditioned by:gender (das Auto), case (here Nom or Akk.) and article or some kind of pronoun (mein/ein).
"deines" is a replacement for "dein Kind" (neutral). Consider this dialog:
Mag dein Kind Tiere?
-- Ja. Und deines?
-- Meines auch. Meines mag nur keine Taranteln.