Hey Beepster,
Took balls to open up. Last time I opened up a different topic, I got fired.
Far as I know, biology has us less attracted to siblings so we don't mate and pass on defective recessive genes. The underlying subconscious check and balance has worked it's way to the conscious level into legal systems and moral dogma. You get horny over your sister and there is no limit to the condemnation you will face if you admit it.
Human instinct to keep the race going is however strong enough to overpower the taboo. Girl in a bikini is a girl in a bikini to a healthy male.
Thanks for sharing, and no condemnation or moralizing on my part. Give yourself a deserved break from any guilt feelings.
John