Wonderful Site! I just found it!
I have a twin sister, a fraternal twin of course. We are extremely close. We share everything in our thoughts. Ever since we were little kids we have been very close. Most twins are very close. We think alike and at times we feel we read each others minds. Growing up together, Mom used to bathe us together as small children and we grew up not thinking too much about seeing each other with little to no clothing.
In our teens and sex was usually the topic of the day we openly exhibited our bodies to each other for thorough inspections and discussions of what felt good. We are so close, I almost feel like I'm cheating on her by sharing this story, but I highly doubt she knows anything about this site.
We were so close emotionally and in every other way. We still are. As a teen I thought nothing of openly asking her if she would jack me off, or she would openly ask me if I would finger her for a while. We did this all the time from about 15 to about 18. It was interesting to see her pubic bush and compare that to my own hair pattern in color and thickness. She would spread her legs and let me spend hours looking at her pussy and playing with it. We enjoyed making each other feel good in a way that is difficult for many people to understand, but it was like we shared one mind. We never thought anything really bad about it.
There were times when my parents went away for weekends leaving us alone at home when we were 15 or so. We certainly were old enough we didn't need baby sitters. We would shower together naked and have fun in the shower, and sleep together and fool around until the wee hours when we both finally fell asleep. We loved (still do) each other in a personal way only twins can understand.
Now for the part I especially wouldn't want her to read ... we experimented doing everything else as well. I will let the readers use their imaginations, but whatever you are thinking you are probably right. On those times when we were home alone all night long especially. We would go at it hard.
We both learned all there is to know about sex with each other. We are both married now, but that bond we share is so strong it will last forever. We didn't fool around again after we were married for about 8 years. Then one time we got together and masturbated in front of each other again for old time's sake and for fun. We haven't made a practice of that though. Maybe we will do it every 8 years or so out of fondness for each other. I love my sister almost like a wife.