Boobs comparison

It was sunday morning, one of the best day of my life, the day I can never forget. I am 19 years old my parents were out of town for the weekend, I was with my sister and my cousin came along to give us company. On Sunday morning both were doing workout and I was just reading a book in the same room. My elder sister, 23 was wearing a tight sleeveless workout top and my cousin sister, 21 was wearing a sports bra. Both were looking a sexpot that day, and suddenly I heard them having an argument, I pretended to read a book but my ears were on their argument. They happened to argue on whose boob were bigger they pretty much have same size boobs still they were thinking their was bigger. After 10-15 minutes of arguing my cousin said, "let's call your brother, he's a boy let him decide" I was shocked after hearing from this but I kept reading my book pretending I didn't hear anything. My elder sister said, " what!! He's our brother, how can we ask him such thing" my cousin tried to take the advantage of the situation and said, " they agree your boobs are small" my sister couldn't take the insul and yelled, "FINE! Let him decide" I listening everything but didn't know how to react, I kept reading. Suddenly my cousin called me, " hey bro, come here, we need a favor"
I kept my book aside and walked towards them,my sister said, " she(my cousin) wants to know whose boobs are bigger and we need you to decide" I acted shocked but then I said," ok lets do it" and took look at both of their boobs like I was analyzing "its quite difficult" I said, I took my hand near my cousin's boobs and grabed it, she seemed fine with it I squized it gently then I took my other hand and grabbed my sisters boob, "what the fuck!! What are you doing" she shouted. "How else can I tell, you want to know who's boobs are bigger or not??" I asked. "Fine go ahead" I was very happy my both hands were pressing boobs of two different women, my boner was out of control, it would have exploded anytime. After sometime I stopped pressing it, and said, " its still difficult, I need you to remove your clothes" my cousin did it without a bit of hesitation. I said," come-on sis its just for the sake of your competition" then she also removed her clothes I saw my cousin sister and elder sister half naked, I pressed their naked boobs for quite a sometime without giving them any answer, my cousin said, " you are enjoying this, aren't you?" I stared at her couple of seconds and she grabbed my dick it was very hard then," hmm I see you erection you perv getting aroused by touching your sisters" before I say anything she pulled my dick out and started sucking it, meanwhile my sister saw everything and couldn't control herself, she sat on her knees and both were licking my dick and we endup doing threesome.
And when my cousin was leaving for her house she gave my goodbye kiss on my lips and said we should do it more often with a naughty smile. And I kept thinking when should I call her again