There's no getting around some governmental involvement with an inheritance, both federal and state. But, honestly, it's not a difficult a process to set up a will and a trust with the right attorney. You go over the options and they craft the document and handle getting it registered. Also, trusts had some protective benefits, besides tax, like a level of privacy regarding one's assets, as well as a layer of protection from lawsuits, especially scams.
But if you want to refuse any inheritance just ask you parents to take you off their list of beneficiaries in writing. Failing that you can always donate all of it to you favorite home for retired cats. You'll still have to declare it.
Try being the executor of an estate some time. That's a lot of work, especially if you're principled. Setting up a trust is nothing in comparison.