Is it normal to have such fantisies over my cousin?

For a good few years I have had a rather odd fantisy over my female cousin. Ever since I saw her wearing a knee length black skirt I can't help but wonder what colour knickers she wears underneath. I have always had a thing about woman and underwear and skirts blowing up like film star Monroe and had many a fantasy of female celebrities flashing their knickers, and that sounds pervy enough! but my concern is I have had the same fantisy over my cousin, it's about her standing over a fan, and as the cool air lifts her skirt I get quite excited. I have never ever been really keen on nudity as it simply does nothing for me, I certainly don't want sex with her, but I find it a little embarrasing. At first I found the whole thing positivly repulsive, but I couldn't help myself and as I continued with the fantisy I got a bit more comfortable about it. I thought about asking her if she would be kind enough to make this fantasy a reality just to satisfy my perverted desire but I'm embarrassed, I certainly don't want any romantic relationship with her, not with my own cousin, though I'm told that to have a relationship with a cousin is possible, or even legal, please reply and tell me if this is normal, Thank you.