Does 両親ともに健在とは限らない。mean "Both of my parents aren't alive."?


This is a sentence from the Tanaka corpus, I would have thought that it means
"I have a parent that has passed away.".

I'm asking that because the Tanaka corpus contains some mistakes so I think it
may be the case here but I'm not sure(some people say that this sentence
doesn't mean anyone is dead).




Strictly speaking, "〜とは限らない" means that there is not a 100% probability that
the thing is true. However, it is used when there is no guarantee that the
thing is 100% sure, but there is a slight probability that the thing is true.

In this case, it means that there is not a 100% probability that the parents
are still alive and well.

In other words, **there is no guarantee that the 〇〇 will happen.**

Example①：（Often used in Manga.） ・彼が絶対に生きているとは限らない

Example2②（when you are not sure if the bus will be on time） ・バスが時間通りに来るとは限らない

