the declaration of independence mentions something called "the pursuit of happiness." the constitution goes on to detail how this concept is to be exercised.
now, just because one can PURSUE happiness here in these united states of america, under the laws provided for in the constitution, there is no guarantee that one can legally ATTAIN one's own brand of happiness.
if practicing homosexuality makes you happy, you go ahead and pursue it - LEGALLY - all you want; just do not expect me to support your effort, legally or otherwise.