Is Katy Perry related to Steve Perry?

Perry was the 97th most popular surname in the U.S., belonging to 212,644 people, according to 2000 US census data. You can be sure that not all of the 212,644 people are related. No, they're not related.

I thought this was just a thing with my parents who think everyone with the same name, is the same family.

It’s not true.

Yes she is. Katy is Steve and Joe Perry's adopted daughter. During the lengthy adoption process, Joe referred to her as "The Joe Perry Project". Steve was initially upset by this and filed for divorce. Joe was later forgiven by Steve, at which point he wrote the song "Anyway You Want It".

Edit - I should add, your questions are very thought provoking.

Perry is a fairly common last name.  It includes Matthew Perry, Arctic explorer.  I had a great aunt who married a Perry, and they had a son Martial Perry.  Not quite as bad as Smith, but a common name does not suggest a relationship.

Surnames are no indicator of biological relationship....... surnames were chosen/given when first taken, so lots of unrelated people used the same name......so it is like assuming that everyone named John is related or everyone named Mary is related

No, she isnt. You're a moron

no, but she is related to katy one-eighty

Yes. He is her distant uncle. Look up the lyrics to Smile by Katy Perry and Lovin Touchin Squeezin by Journey.