It's Much Easier To Marry Your First Cousin Than Your Same Sex Partner - Texas, I'm Looking At You.

Apparently it is much more common and certainly more legal to marry some one that shares a big hunk of your genes (hello, recessive gene pairs) and risk congenital anomalies than it is to marry some one who only shares your assemblage of genitalia and poses no risk of congenital anomalies.

 And in a related story:

Peace.  Out.