Never with a brother or sister, but I had some great sex from a cousin. It all started one night when i walked her to her car after a party out our house ended. Her car was parked far away and it was very cold. I got in her car while she warmed up the engine. After a few minutes she was sucking on my cock. Oh my, it was so good. She is a nurse and nurses can really give good head. After about 10 mins. of her sucking me off I shot my load down her throat. mmmmmmmm it was so good. We started from there 6 months of fucking and sucking.