I have had several perms over the years and my hair always went back like it was. As it grows the roots come in however your hair was before just like if it was dyed. The ends retain the perm till it wears out or you cut it.
I would like to say it does, but i have actually had an experience with my sister where she had beautiful straight hair. She decided to do a perm, and her hair never was the same. It is now ver curly and full!