I think if you're attracted to an 18 month year old, pimarily you're sick, rather than gay or straight.
I'm going to write something pretty offensive here, buy bear with me...
I can 'understand' (but not condone) someone who is attracted to say, a 15 year old. There's that while St. Trinian's thing (which frankly, turns my stomach).
But I will never be able to get how someone could have sex with an infant. It just doesn't compute. It's like being attracted to concrete, or daffodils.
I await the brickbats.