Accessing Wiki Data that's similar to the actual wiki page

Question

wikidata url: https://www.wikidata.org/w/api.php?action=wbgetentities&ids=Q254138&format=json&props=claims

The part I'm currently looking at is genre, which is P136. This only contains one genre in it, and that ID links to "heavy metal music" Q38848

Looking on the wikipedia page https://en.wikipedia.org/wiki/Slipknot_(band) there are three different genres. Why do I not have 3 genres in this property?

Answer 1

It looks like this is because that information simply doesn't exist in wikidata