the use of した to modify nouns


Recently I came across this phrase:

> 血液型に関係したことって、日本では、すごく人気がある

Why is 関係した in the past and not in the present? In this case, is there any
difference between them?




Consider the English verb _relate_. We commonly use the past-tense form as an
adjective.

> 血液型に **関係した** こと  
>  ↓  
>  things **related** to blood type

This is one of those uncommon areas where the Japanese and English grammar
line up -- likely due to the shared underlying nature of the concept. The
relation itself is something that is _already established_ , so we use the
past tense (or completed aspect, if we're being more specific).




Consider the English verb _relate_. We commonly use the past-tense form as an
adjective.

> 血液型に **関係した** こと  
>  ↓  
>  things **related** to blood type

This is one of those uncommon areas where the Japanese and English grammar
line up -- likely due to the shared underlying nature of the concept. The
relation itself is something that is _already established_ , so we use the
past tense (or completed aspect, if we're being more specific).

