Born this way

One of the arguments of the “alternative lifestyle” crowd is, “We were born this way.”  In essence, the argument is built on the idea that one is born with certain passions/desires/preferences in regards to sexuality, therefore we ought to follow this path.  But is this really a valid pursuit?  Is this the way we ought to handle the passions or desires we have?  Is it valid to argue that these desires exist therein, therefore we ought to fulfill them?
What if our desires include pedophilia, bestiality or cannibalism?  Obviously, I am choosing extreme and/or perverse categories, intentionally.  One can include any desire one wants and the argument remains the same.  Does the simple existence/presence of a desire automatically legitimize that passion?  Does the possibility of a moral standard have any say?  We can offer arguments as to why it would be wrong to simply give into the passions of bestiality or cannibalism and most would agree.  But why do we agree with these arguments, based on particular foundational arguments, but not others?
It comes down to what we hold as foundational or authoritative.  For the Christian, the Bible and the teaching of the historic Christian faith has always identified LGBTQ as sin.  Can one really look to personal preference for foundational truth?  If we reduce truth to individual preference, we have gutted truth of any authority or legitimacy.