Hello again
"Τίνος" does NOT have a gender but apply for all 3 of them ! (masculine-feminine-neutral).
We ask with "Τίνος" when we have absolutely NO clue what gender we might recieve as an answer.
On the other hand "Ποιανού" or "Ποιανής" is when our question is suspected to recieve a masculine or feminine person AS an answer
and there is NO neutral word like "Ποιανό" <--- does NOT exist such word.
BUT with "Τίνος" we imply ALL 3 genders... for example "Τίνος είναι αυτή η γάτα" (whose is this cat?)
and we might recieve as answer "Αυτή η γάτα ανήκει στο μικρό αδερφό της Μαρίας τον Πέτρο" (...This cat belongs to Mary's little brother, Peter") (kids are supposed to be neutral in general)
And yes in Northern Greece (mainly in suberb areas), we use too the phrase "Τίνος είσαι εσύ;" (meaning "whose child are you"... in general)
hope i helped