I would have to agree with those who have posted that it is between the two parties involved and not the concern of others. Sexual preference, whether it be gender, age, appearance, or any other attribute is and should be a non-issue outside of the relationship. That is not to say that there aren't laws that need to be heeded, there are and for good reason. It does mean that if you are into 18 year old albino midget double amputees with an overbite who like bathing in cod oil, Neil Sedaka, and also being tickled WHO CARES! If it makes you and your odd little friend happy, good for you!
For me, I've dated and played with women as much as twice my age and women as much as half of it. (I'm 38 now so this is a recent development...like this month.) I've had much fun with both. Are there some complexities involved with a large age gap? Yes. I'm dealing with some now. In the grand scheme of things, does this make such encounters or relationships impossible or ill-advised? I don't think so.
The way I see it, if it isn't illegal, doesn't hurt anyone, and doesn't make anyone unhappy then by all means, go for it.