Outgrown by my sisters

I'm a 19 year old guy living with my mom Aarti, and sisters Sita and Geeta, my mom is a tall woman at 6 ft, but we three siblings doesn't seem to have her genes and are short, I'm a pretty short guy at 5 ft 4 and my sisters both near 5 ft 1,

We were playing near our swimming pool, when Sita said " bro all of us have same foot size did you noticed even if you are taller than us "she said putting her leg next to me . actually she was right even if I was taller my and my sisters foot have the same size," but see my hands are much bigger than yours" I said comparing my hands with Sita " yes I can fold my fingers over yours " I said, " so you might grow like mom, brother" said Geeta, " I always wanted to grow taller than her " said Sita, " wait lets measure on that wall" I said as I grabbed a marker from the window of my room, " well we are much below Ram" said Geeta looking at the measured marks of our heights, " looks like he only inherited moms genes" said Sita," Yesss!" I exclaimed, " Anyways let's dive into the pool now" I said as I dived.

A month passed and it was time for Sita and Geeta to go back to Hyderabad for studies, they studied at the top university in the Hyderabad, well I was not so good at studies. I really felt bored when they both were not around, they were more like friends to me than sisters. a year passed, I missed them so much, we often talked in the video calls.

One day when I came back from the college at night my mom gave me a good news, that my sisters are back from Hyderabad and are already having bath in swimming pool, I jumped with joy,I changed my cloths and ran towards swimming pool, 

" Hi Sita, Hi Geeta " I shouted, " Hi Ram " they both shouted back,I dived into the pool we three hugged each other, " I missed you both so much " I said, " even we did Ram " said Sita, you must gave felt bored at home alone right" asked Geeta " Yeah thats why I joined gym, and even made some muscles " I said flexing " oh wow " both said at the same time, then we just talked, talked and talked until our mom called us " oh you guys come out now, or you'll will get cold " she said we both hurried outside looking at her anger, Sita and Geeta climbed up and I was just about to climb when I saw a amazing view both are now grown like women and were filled with the curves at the right places, my hormones start tickling, I couldn't keep my eyes from them, they both were turned behind and talking to mother when i climbed up, and my mouth dropped, both girls are not only filled with curves at right places but are also grown lot taller, they were built like amazons, so before they could notice my current height I again stepped into the pool, listening to their conversation with mother.

Suddenly my mother turned towards me and said " Don't you think Ram, our girls are grown up " she asked " uh yes" I stammered while answering, all of sudden Sita noticed the marks we made on the walls a year ago," lets check how much we've grown Geeta "said Sita as the stands next to wall " oh it comes below my shoulder " said Geeta " mined too" Sita exclaimed happily. " Come Ram let's check your height" Suddenly Sita said, I became afraid, my heart started beating even faster, I slowly climbed up, and they were all surprised too see my true height " by looking at your faces I can make than youll are surprised that I didn't grew as much youlll did " I said in embarrassment, " yes Ram it's kinda funny that a year ago you were taller than us both and we passed you not even knowing " saud Sita, and both Geeta and Sita burst into laughter, " sorry to say Ram but you inherited your father's height, you'll never met him, bit ill say he was short " said Aarti, " thanks mom for clearance " I said Sita then placed her hands next to me to compare " See Ram now I can fold my fingers over yours like you did a year ago " she Said laughing " wait a min brother can you please flex your biceps for once " said Geeta, I did as she said she then placed her arm next to mine and said " See we were simply amused when he showed his biceps sometime ago, when we have ours bigger than him" she said,I noticed that she was right her biceps were much larger and more defined than mine,I tried to move away from there to avoid anymore embarrassment, but Sita Suddenly pulled me towards her and pinned me to the wall with just one hand, I was really surprised that moment at how she became so much powerful in a year, lately I started getting erection, I tried to hide but my hands were pinned my Sita, " oh see our little brothers little member is getting hard" said Geeta, " yes his hard member is the only thing he has which is bigger" said Sita and both girls burst into laughter, I stayed there embarrassed, pinned by my sister.