don't pollute your argument with things that are wrong.
I realized as soon as I saw this on Facebook that it is wrong;Texas does not allow first cousins to marry (as of 2005). I wondered if this other parts of it were as well. Short answer: sort of.
The danger in something like this is that it is so easily proven wrong that it dilutes your argument. Anyone arguing in favor of gay marriage because something at least as icky to most folks is legal will first have to argue their way out of obvious errors on this map.
Being perhaps a bit too fond of this sort of research, I decided to fire up the old search engine and go prospecting.
What interests me are the states that display some level of hypocrisy. There are 19 states which allow first cousins to marry, but not homosexuals. Arizona, Indiana, Utah, and Maine all allow first cousins to marry if the couple will be unable to reproduce, which of course shoots one of the main arguments against gay marriage (that marriage exists as a social construct in order to promote a healthy environment for children to be raised) right in the foot.
Two states do things the other way around: Iowa and New Hampshire allow same sex unions but not first-cousin marriage. Illinois is unique in that it allows cousins to marry if they cannot have children, and allows for civil unions. So they are very good at putting conditions on civil rights, which will surprise exactly no one.
So, I came up with an infographic of my own, of sorts. For purposes of fairness, if civil unions are allowed, I marked the state as allowing gay marriage, just the same as I marked the state as allowing first cousin marriage if it is allowed only in certain circumstances. Most states allow neither. North Carolina has an odd restriction on cousin marriage; something called "double first cousins" are not allowed to marry, although all others are. I'm not entirely certain what double first cousins are; I'm guessing the offspring of two sets of identical twins (if an identical twin marries an identical twin, and their twins also marry, the cousins will be genetically the same as siblings).
Anyway, here is the graphic, which to the best of my knowledge is accurate and up-to-date. I still wouldn't hang an argument on it, not when there are so many in favor of gay marriage that are not subject to change.
Clicky for biggie.