Out of curiosity and as a non-native english speaker:
"their"?
Ah. yeah that could be confusing (because English is not confusing enough). While English favors gendered pronouns when talking about a single person (he/she, his/her) and 'their' is typically used to describe a group of two or more, 'their' can also be used as a genderless alternative to his/her.
This convention has been used as a safe way to address a person when their gender may not be known although that is not a hard rule, it has long been acceptable to use the genderless 'their' based on the author's feel of how best to construct the sentence.
In recent years the use of 'their' in this context has increased as people have a greater understanding and empathy of how people want to be identified when they do not wish to be identified by gender at all. (It is increasingly common to see (he/his) (she/her) (they/their) in twitter profiles and email signature blocks so that when people are responding, they can use their preferred pronouns (see what I did there? since I wouldn't know if the subject was male or female, I used their even though i was talking about a singular hypothetical person).
Hope that helps!