The two forms of singular "they"
Wikipedia describes two usages of the singular they:
The epicene they, used for indeterminate gender: "The student failed their exam."
The generic they, used for indeterminate number: "Anyone who thinks they might be affected..."
The use of singular they, though, seems illogical when used with a gender-specific word. In this case, a gender-specific pronoun would make more sense: "a good mother loves her children"; "the youngest son thought his parents favored him".
Conversely, a gender-specific pronoun used with a gender-neutral word has fallen out of favor nowadays, so the singular they would be better to use in this case: "a good parent loves their children"; "the youngest child thought their parents favored them".
