So then the right to specific health care for what's in one's underwear should be denied based on that reasoning?
You're not into the whole "logic" thing are you?
Maybe you should start learning about it.
Start with looking up the term "non sequitur".
Now, look up the term "red herring".I take it you are unable or unwilling to answer the questions.
If its the consensus of society that marriage is simply a union of two consenting adults, there's no need to prohibit any two person, consenting adult, union, including blood relatives. Why should it matter who marries who, or who can't marry who?
There might be good reasons for preventing certain parings.
But there aren't any for preventing same sex parings.