I would like to adopt my 19 year old nephew. Can I do this in PA without an attorney? I heard it's expensive. Can I just fill out some paperwork and file at the local courthouse?

You CAN do an adoption without a lawyer.

You can ALSO set a bone yourself with a splint and skip the doctor.

I wouldn't recommend EITHER.

But--if you insist on it, contact your local county clerk's office and ask them what forms are needed for an adult adoption.