What is the nearest relative one can legally marry?

It is my understanding that as per Florida Statute 741.21, a man may not marry any woman to whom he is related by lineal consanquinity (that means descended from the other as in Father and daughter, Mother and son), nor his sister, nor his aunt, nor his niece.  A woman may not marry any man to whom she is related by lineal consanquinity either, nor her brother, nor her uncle, nor her nephew.  So it appears that the nearest relative that one may marry may be a first cousin, which is the law in New York as well.   You should double check this with either an attorney or the marriage license bureau in Florida.