If You Adopt Your Girlfriend, Is Having Sex with Her Now Incest?

The Volokh Conspiracy » If You Adopt Your Girlfriend, Is Having Sex with Her Now Incest?
The article’s abstract reports that, “For some time now adults — both heterosexual and homosexual — have been adopting their lovers and spouses all over the country for various reasons: to better guarantee the adoptee’s right to inherit directly from the adoptor; to keep collateral relatives from having standing to contest the adoptor’s estate plan; or to add a loved one to a class of trust beneficiaries (allowing the adoptee to inherit “through” the adoptor).”
And the article reports that about half the states “are subject to statutory or common laws that include the adopted parent/adult child relationship within the definition of incest.”