Why do clavicle bones stick out on some women and not others?

Genetics or Injury: This is a common question and unfortunately, without x-rays there is no way to answer why your clavicle is shaped the way it is, but i will give you some basic information. You are probably talking about the ac joint (the bump near your bra strap). Some people have more enlarged joints naturally, some get early arthritis, and some may have had an injury leading to ligament laxity. Hope this helps.