Question

In Old English, the pupil of the eye (the round, dark center) was called the 'apple'. It was thought that the pupil was a round object much like an apple. When you look at someone, 1)their reflection appears in your pupil. So if someone is the 'apple of your eye', he or she is someone that you look at a lot and enjoy seeing.
------------------------------------
1)their reflection.....

Is "their" grammatical? What about "his or her"? Or what about "his" (reflection)?

Answer 1

Since the antecedent is "someone" (obviously singular with "one" in it!), the pronoun "their" is incorrect. See below.

<i>In Old English, the pupil of the eye (the round, dark center) was called the 'apple'. It was thought that the pupil was a round object much like an apple. When you look at someone, <b>his or her</b> reflection appears in your pupil. So if someone is the 'apple of your eye', <b>he or she</b> is someone you look at a lot and enjoy seeing. </i>

Answer 2

Thank you....
Can we use 'their' instead of 'his or her' in a casual speech (in everyday conversation)?

Answer 3

Lots of people do that. It's incorrect, but they do it anyway!!

=)