Applying the definition of marriage to real life application.

Look, the tide has turned sufficiently for public opinion now to accept that gays have the same rights as straightsand that

these rights should include the right to enter into certain types of contractual obligations, e.g. marriage. It is that

simple.

A guy comes to a2k not to argue but to clear the confusion on the matter, and I get blamed for "supposedly" making an argument for incest couples to marry?

First cousins are not really considered incest.

What is the reason that Incest couple remains a taboo while being gay is not?

Incest is sexual intercourse between close relatives that is illegal in the jurisdiction where it takes place or is socially taboo (or both) and can be illegal or legal depending on the jurisdiction.
The exact definition, including the nature of the relationship between people, and the types of sexual activity, vary by country, and by even individual states or provinces within a country. These laws can also extend to marriage between said individuals.
When incest involves an adult and a child it is considered to be a form of child sexual abuse.

In the United States the District of Columbia and every state, except Rhode Island, have some form of codified incest prohibition.[28] However, individual statutes vary widely. Rhode Island repealed its criminal incest statute in 1989,[28] Ohio only targets parental figures,[28] and New Jersey does not apply any penalties when both parties are 18 years of age or older.[28] Massachusetts issues a penalty of up to 20 years' imprisonment for those engaging in sexual activities with relatives closer than first cousins[28] and Hawaii up to 5 years in jail for "sexual penetration" with certain blood relatives and in-laws.[28]
In all states, close blood-relatives that fall under the incest statutes include father, mother, grandfather, grandmother, brother, sister, aunt, uncle, niece, nephew, and in some states, first cousins, although Rhode Island allows uncles to marry their nieces if they are part of a community, such as orthodox Jews, for whom such marriages are permitted. Many states also apply incest laws to non-blood relations including stepparents, step-siblings, and in-laws.[29]
UCLA law professor Eugene Volokh has questioned the rationale behind laws prohibiting incest, at least as they apply to sex between adults.[30]

Extremes for simplicity sake, sorry, if that was a mistake.

I did not have intentions to "argue" or "obfuscate."

Quote:

First cousins are not really considered incest.

Didn't know that, so in the past such relationships were incest, but now it is not.
It seems the politicians are changing the definition as need by the people who make it see how it fits their lifestyle.

This only gives more proof that it depends on the politics of a state.

It is simplistic and it is fallacious