The mysteries of size> back
July 9, 2011
Question of the Week: "Why do I barely fill an A cup bra while my best friend, who is my height and weight, easily rounds out a D cup? I mean, is that really fair?"
Great question…and the short answer is…blame your parents! That's because all three of the factors most responsible for determining your ultimate cup size are highly influenced by your heredity.
Your Genes: The moment you're born, you already have a predisposition toward your grown-up cup size. That's because you inherit a gene for breast size (either active or dormant) from each of your parents. The gene for breast size may either be active or dormant in any given generation, so your D cup mom could easily pass on an active A cup gene to you, even though it was dormant for her.
Your Hormones: I was surprised to learn that after puberty, we all have a pretty similar amount of glandular tissue in our breasts, but it's our genes (thanks again, mom and dad!) that determine their growth potential once 'the girls' are exposed to estrogen hormone. You definitely witness this relationship on a monthly basis if you're prone to dramatic changes in your own breast size as your hormones swing up and down around the menstrual cycle or when you go on or off 'the Pill'.
Your Body Fat: Okay, our parents get a little reprieve on this factor, since how we eat and move usually has the greatest effect on how lean we are. Breasts are a natural storage area for extra fat, so overall higher body levels usually mean a bigger breast size. But that perfect relationship can break down because your inherited genes also dictate where on your body those fat cells gets stashed. If you're an 'apple' body type, extra pounds tend to get stored in your breasts and mid-section first while your hips stay narrow; if you're a 'pear', you may find your hips and thighs getting curvier as you gain pounds, while your breasts hardly budge up in size at all.
Bottom Line: So if you're a 34A (small torso/small cups) and your BFF is a 34D (small torso/large cups) and you actually are the same height and weight, chances are most of the difference in your bra sizes is due to genetics and hormones rather than body fat levels. Her breasts are larger because her genetics gave her more growth potential, and she may have had higher hormone levels that boosted growth to the maximum. If you're still bummed about being an A-cupper, don't forget that when it comes to playing high-impact sports, smaller is always easier!
Thanks, and have a beautiful, active week!
Introducing Champion's Sports Bra Expert - LaJean Lawson
In 1977, Champion Activewear invented the first sports bra, called the Jogbra®, made from two jockstraps sewn together. The realization that women also needed support for their assets was the catalyst for Champion Activewear to apply innovation and technology to become the leader in the sports bra market.
In 1977, runner LaJean Lawson had just finished her first marathon with bleeding sores on her shoulders and chest from a bra that did anything but support. Her search for a solution eventually led to the discovery of her life's passion–sports bras!
Today, Champion Activewear is thrilled to offer Dr. Lawson as a resource to help you solve your sports bra problems. While Dr. Lawson has gained critical knowledge from scientific research, the best education she's had about sports bra needs has come from the thousands of women she has spoken to at races and events, as well as those who help her test Champion products.
Whether it's your shoes or your sports bra, your workout happiness depends on finding the gear that's just right for your size and activity level, and that's exactly why we're here to help!
Shop Sports Bras
Ask our expert, LaJean
Try our bra finder
Check out bra videos