Loud Thunderstorm, Lightning and a Blackout

I 24 live with my sister (twin) we rent an apartment off campus, not much into partying and prefer studying. Well off due to family wealth and trust funds, a Friday night was just like any other night for us after dinner we studied and then went to our beds. I was awoken by a very loud thunderclap right overhead, usually thunderstorms don't bother me. But this one was like war had started outside my window. My sister never liked thunderstorms and so she came running into my room and got into bed with me and hid under the covers. Cuddling closely up to me, I'd started sleeping naked a few years earlier and at first my sister didn't notice. Too scared by the storm outside, she was only wearing thin cotton PJ's short sleeves and short bottoms. As the storm moved away, she relaxed, the power was out and so she decided to stay with me till morning. It was only then she realized I was naked, slightly shocked at first. But quickly got over it, she wanted to see my naked body for educational purposes she claimed. I used the old phrase you show yours I'll show you mine. Okay she said and totally removed her PJ's using a flashlight we examined each other's bodies. She was about to redress when and another thunderclap went close by and she again cuddled into me, only now she was totally naked like me. As we laid cuddling together, I got aroused and my cock poked her. She started playing with it and we ended up becoming lovers, no protection was used. But we were careful, having sex again in the morning. We now have regular sex and enjoy our newfound relationship very much. All because of a thunderstorm and a blackout, which I love now more than ever before.