Is incest the new homosexuality?

A professor in New York has been accused of incest with his adult daughter. Both sides were consenting, so why is this still illegal? Most stories are drawing parallels with homosexuality and incest. If both parties are consenting then why is this so bad?

My first answer (besides claiming some moral grounds based off a standard set by God, which I doubt would fly for most people) is the biological one. Think of the offspring! But now days there are so many contraception tools that offspring need not be connected with sex anymore. And if a biological argument against incest can be made, why isn't there one for homosexuality? No offspring can be produced in a homosexual relation, therefor it is against biology. This argument is generally counted by something like: this is about love between two people, that knows no bounds. Why isn't it same with incest in this case?

An argument that says homosexuality is different to incest isn't based off consent, (or even faithfulness and monogamy) but its based off who you are. But if who you sleep with defines who you are if you are gay, why isn't it also the same for heterosexuals?

Back in the day it might have been a news story if a professor was gay, and he probably would have been socially stigmatized for being so. Today that is not the case. Although some backwater places still deem homosexual behavior illegal, (look at recent news stories about FIFA, Qatar and gays). I wonder if the same thing will happen with incest? In say 50 years (or less) will people look back on us and think we had backward, oppressive laws?

Maybe in the future, people in Australia won't need to sign a stat dec before they get married to say they are not related to each other (and that they are not already married to someone else). One day we might be progressive and open to all people. It seems that China, France, Israel, the Ivory Coast, the Netherlands, Russia, Spain and Turkey have already beaten Australia to the mark.

William Saletan on Slate.com runs through an argument as to why homosexuality is ok and incest is bad: because Incest is Cancer to the family (but doesn't everyone have a right to do what they want in their own family? 8 other countries don't seem to have an issue with this). Al Mohler also posted on this topic, responding to the Slate article: So Why is Incest Wrong?

Finally Doug Willson sums up his article with: "Do you object to a guy bonking his sister? You, my friend, are clearly filled with hate."