Is this grammatically correct?

Hi~ is it correct in grammar to use the plural pronoun "them" in this context, instead of "him/her"?

Thank you~

Most people who see someone think the same things about them.
Have the students recall how they shared opinions concerning the pictures they saw earlier.
–– Perceptions Are Reality (What you think, you believe to be true.)
–– What you think about someone determines how you will treat them.