When I was in college (undergraduate), from ~18.y.o. to ~22.y.o., our local chapter of my national fraternity had an unofficial relationship with the local chapter of a national sorority. The freshman pledging sisters of this particular sorority were paired up as "Little Sisters" of the sophomore-thru-senior active Brothers of our fraternity. And, the freshman pledging brothers of our fraternity were paired up as "Little Brothers" of the sophomore-thru-senior active Sisters of this particular sorority.
Our fraternity was made up primarily of non-football athletes. There was a different fraternity on campus that was almost exclusively American football players. And, our "Little Sisters" sorority was (likewise) made up primarily of non-football affiliated female athletes (mostly swimmers, divers, gymnasts, and runners). There was a different sorority on campus that was almost exclusively made up of the American football affiliated females (cheerleaders, pom-pom girls, football team volunteers, and other girls who just wanted to hang out and hook up with the football players).
For the purposes of this post, I will refer to our fraternity as the Nu Zeta Pi (NZP) Fraternity and our "Little Sisters" sorority as the Sigma Beta Gamma (SBG) Sorority.
This was back in the days when it was commonplace for fraternities and sororitities to have some pretty, shall-we-say?, "interesting" (often kinky) pledging rituals. For example, fraternity/sorority paddles were frequently used to train/discipline pledge brothers/sisters (and, if necessary, active Brothers/Sisters). Now-a-days, anything similar is considered "hazing", because there are always those who will take a good thing too far, and ruin the fun for everybody.
I fabricaed my entirely fictional "NZP" slang nickname above (as a replacement for the fraternity's actual name), but the SBG name was actually the unofficial slang nickname of our "Little Sisters" sorority (the actual/real name was/is something else). SBG stood for "Small Breasted Girls" (LOL). In addition to being an athlete, having small breasts (not larger than B-cup) was obviously an unofficial/unspoken requirement of receiving an invitation to pledge the "SBG" sorority. Females with bigger breasts usually ended up in either the football-affiliated sorority that I mentioned above, or some other sorority, or remained independent. When I was at this college, there was not a single SBG sister with tits larger than smallish (very firm and upwardly-thrust) C-cups, and there were only a few of them (smallish B-cups and SMALLER were the norm).
I remember being attracted (physically/sexually) to larger breasts at a younger age (junior high school and high school), but this changed as I spent my college years socializing almost exclusively with small-breasted sorority girls. As freshmen "NZP" and SBG pledges, during joint/combined (fraternity & sorority) pledge "training/disciplinary line-ups" (especially during "hell week"), we were often stripped naked during some of the pledging rituals (including disciplinary paddlings). So, I saw a LOT of tanned bare bottoms (male & female), and bare SMALL female breasts, during my college years.
One of my favorite rituals was the whipping of little sisters' bare breasts with a small leather strap! During my sophomore year (my first year as an active fraternity Brother), I was paired with a freshman (pledge) little sister who was a cross country runner. She had the smallest breasts of all the SBG pledge sisters, but she was not totally flat. Her AA-cup breasts were just big enough to nicely fill her AA-cup workout/training bras. During the SBG pledges' wet t-shirt contest (no bras allowed), her breasts were just big enough to firmly push her erect nipples against the fabric (she won the contest). When she wore her push-up underwire bikini top, her breasts were just big enough, as they were pushed up and together, to display the smallest possible amount of bare-flesh cleavage bulges outside/above the perimeter of each cup. When she was required to stand before me (naked), with her hands behind her head (fingers interlaced), with her bare chest/breasts/erect-nipples thrust forward towards me, and required to ask me for punishment ("I have been a very naughty Little Sister, Sir. Please punish my breasts, Sir."), I almost had a spontaneous ejaculation/orgasm! It turned out that she LOVED having her breasts whipped, and I was more than happy to satisfy her desire during the remaining several years that we were in college together.
By the time I graduated from college, I no longer had a strong physical/sexual attraction to anything bigger than firm, upwardly thrust, B-cups, and actually preferred A-cups.