We hear a lot of grammar myths growing up. Some come from our parents, some come from our teachers, and some come from English experts. One of those myths is the idea that you must never use “that” as a relative pronoun when referring to people.
The so-called rule goes something like: use “who” for people and use “that” (or “which”) for things.
The problem with this line of thinking is that “that” has not only been used for centuries to refer to people, but also it’s filled that purpose much longer than “who” has. Consider this:
“That has been the standard relative pronoun for about eight hundred years and can be used in speaking of persons, animals, or things. Four hundred years ago, which became popular as a substitute for the relative that and was used for persons, animals, and things. Three hundred years ago, who also became popular as a relative. It was used in speaking of persons and animals but not of things.” —A Dictionary of Contemporary American Usage (p. 555):
Even the King James Bible—now over 400 years old—is littered with uses of “that” as a relative pronoun for people. Here’s one I came across a couple of days ago:
“And the Lord thy God will put all these curses upon thine enemies, and on them that hate thee, which persecuted thee.” (Deut. 30:7)
Actually, that’s bonus reference because it also uses “which” instead of “who”. :)
I personally prefer using “who” because it sounds better to me, but that’s all it is: a preference.