Parent-child incest has the power dynamic issue. It’s basically impossible to consent in that relationship. As to siblings, I’d argue that the logical conclusion is that it is probably okay, unless there’s a limit to how much birth defect risk is allowable, which as noted above, comes with other issues.

Sooo anyone in Congress going to ask how the executive branch unilaterally withdraws from Senate ratified treaties? No? I guess I shouldn’t be surprised.

Are you sure it’s engineering you adore. Left as an exercise for the reader? That’s physicist speak.