If I got an MIP when I was 17, but it's on my adult record, will it be there forever?

It will be there forever, but generally, after 10 years people will ignore it. You are choosing a sensitive career though, so it will depend on the language of the contract. You will be given a background check, so they will see it. If you are required to disclose convictions for the last 10 years, that is different than providing felonies for the last 10 years. You will probably want to steer toward the public school route, rather than the private school route for the first several years of your career.

Hence the term "record."

And all your future employers can search and find it.

And if you don't put it on your application, that is fraud and grounds for dismissal.

In California you cannot be fired for molesting a student,

but you can be fired for that.

Odd, isn't it?

Did you not apply for youthful offender? Usually they will drop it if you get in trouble when you're young.