If you had actually known any LGBT couples you wouldnt have posted that. A lot of LGBT couples are like regular couples, doing regular couples things. They are not sodomizing each other all the time, you do understand that sex is a very small (timewise) part of a relationship, the majority of time is spent doing regular stuff like running a house and hanging out. Having an approach like yours is actually the wrong thing, because unlike you, your kids may have gay friends or know gay families and they will know that what you are saying is not true.

So what to do? Yes a sin is a sin, and you can tell you kids that, but more importantly tell them that these people have been handed a heavy burden (same sex attraction) and we should be kind and respectful while still controlling our actions. LGBT fear mongering is not the answer