I personally think incest will be next to be legalized. Any scientific/medical objections can be answered with contraceptives. Besides, there is no requirement for civil marriage that the couple be in love or fertile, etc. So, if a brother and sister wish to be married to have the same legal rights and benefits as any other two people (or if they simply are degenerate perverts), what justification is possibly left to stop them None.
Also, this new right to “dignity” is even more expansive, open-ended and subject abuse than the old so-called penumbra of rights. Think: the “right to die with dignity.”
That's very astute thinking and reasoning.