- Not only his friends but also John did not attend his classes.
- Not only his friends but also John did not attend their classes.
Which personal pronoun is suitable, his or their?
- Not only his friends but also John did not attend his classes.
- Not only his friends but also John did not attend their classes.
Which personal pronoun is suitable, his or their?
Not only --- but also --- falls under correlative conjunctions. Others include include Either ... or, neither ... nor.
Oft-suggested advice in cases like these is to match the pronoun with the closest noun, thus use his. One reason is because if you use their, as in your second sentence, then a straightforward reading means that John also did not attend their classes, and the sentence tells us nothing about John attending his own classes.
When you use correlative conjunctions, be careful about pronoun agreement.
If you connect two antecedents with a correlative conjunction, the second one must agree with the pronoun that follows.
Neither Yolanda nor the cousins expressed their disappointment when blind Aunt Sophie set down the plate of burnt hamburgers.
Neither the cousins nor Yolanda expressed her disappointment when blind Aunt Sophie set down the plate of burnt hamburgers.
When two words are joined by or, either…or, neither…nor, not only…but also, the pronoun agrees with the noun closer to it.
Either the students or the teacher will bring his laptop to the presentation.
Either the teacher or the students will bring their laptops to the presentation.
Not only the teacher but also the students were reading their books.
Not only the students but also the teacher was reading her book.