Boobies. The girls. Whatever you call them, breasts are surprising for those that have them and those that don’t. Turning up around puberty for women, estrogen and growth hormone cause the development of breasts, which are made up of glandular and fatty tissue.

Here are nine more things you may not have known about the mammaries. After all, they are our breast friends.

1. Smoking Makes Boobs Sag

If there weren’t already dozens of reasons to quit smoking… Not only does smoking cause cancer, increase your risk of heart attack, ruin your teeth, and reduce your lifespan, it is also proven to cause sagging in breasts. In fact, it has been said to be one of the most prominent causes for sagging breasts. There is a vital protein in the skin called elastin, which gives skin elasticity and stretch without tearing. Continual smoking can actually break down this protein, causing slack bosoms.

2. Boobs and Excercise are not best friends

Any runner can attest to this fact. Boobs are not good sports in the world of sports, which is why so many women work as hard as they can to flatten them with sports bras during the act! Also, breast discomfort and even pain during or post-exercise is totally normal. It sucks, but it’s normal.

3. Boobs are not Symmetricak

One of the biggest misconceptions about boobs that both men and women get—thanks to adult movies and media—is that each pair is identical. In fact, one breast is usually larger than the other. Florence Williams’ book about breasts totes that one breast may be 1/5 of a cup size larger than its counterpart. Remember, they’re sisters – not twins!

4. Most Women are unhappy with their boobs

So let’s take a minute to get tittie-real. The vast majority of women aren’t adult film stars, nor do they have the money to get a breast augmentation done. Most breasts don’t look like they do in movies or adult films, so stop thinking that they should be. Natural breasts are awesome, and men love them. So why worry? Survey found out that 70% of women surveyed wished they could change the way their boobs looked. That’s not to say they’re unhappy specifically with their breast size, but nipple size, length, areola color and size, breast shape, and symmetry are all factors to consider.

5. Most Women buy the wrong bra size.. ON PURPOSE

Ever since the big reveal on Oprah that most women were wearing the wrong bra size, women everywhere have marveled at how they could have done so for so many years… yet they still do it! According to data, 85% of women are wearing the wrong bra size. What’s more, they buy the wrong size on purpose. Why risk misshaping your breasts, or having them burst out of the top of your bra for the ultimate discomfort? The truth is, women lie about this for the same reason they lie about other dress sizes: they want to appear bigger, or smaller than they actually are. That’s right, many women are up-sizing bras to come off as having bigger breasts.\

6. The Average bra size is…

By now, we should all be aware that there are no “average” breasts around, right? Size, shape, symmetry… nothing is perfect, and no breasts are identical. However, there is an average breast “size”! That’s right, the average breast size according to recent studies rolls in at a 36C!.. Do you agree?

7. The Average Boobs weight is…

This is a small but fabulous breast fact. The average weight of one breast is 1.7 lbs. Tiny, but powerful!

8. Guiness World Record for the Biggest Boobs is..

Okay, now the enormous ones! According to the Guinness Book of World Records, the biggest all-natural breasts on record belong to Annie Hawkins-Turner who is sporting a US size 52I! Guinness says that while 52I is the largest available size in America, Annie’s bra size would likely be more of a 48V if such a size would be manufactured. Ooshey!

9. Breasts are made out of milk… sorta

Have you ever noticed how your pregnant wife’s are suddenly sporting massive boobies? No, it’s not plastic surgery for the pregnant. According to Discovery Health, the majority of the female breasts -pregnant or not- is made from milk and tissue! That’s right, the average female breast contains anywhere from 15-25 milk glands that interweave with milk ducts and connective tissue! So the next time your pregnant friend pops out a kid and turns her 32A’s into 34D’s… you know exactly what’s causing the ballooning situation!

10. There are more than 4 million new bras produced everyday