There are lots of silly myths about boobs and the like.
I have been quite a few different sizes in my time, 38c at 16, 36b at 21 I had lost some weight by then), then when I got pregnant and breast fed they went enormous and very tender and sore, (as you would expect for a while), they were not nice to have to carry around at the time, they didn't feel like they belonged to me, so I have seen it from all sides and I think a 36b or c is a good size, I preferred it when I was around that, not too much not too little, and when they got bigger than that I put weight on everywhere else first but when I lost weight guess where it goes from 1st pffft yep boobies lol.
Another thing to remember on the serious side is that MEN can also get breast cancer and need to do checks of their own, and because people don't expect it in men then they need to be just as vigilant.