Researchers are currently unsure as to the actual cause of pectus excavatum but assume that there is a genetic component for at least some of the cases. Approximately 37% of individuals with pectus excavatum have a first degree family member with the condition.[2] A number of genetic markers for pectus excavatum have also been discovered.[11] Physiologically, increased pressure in utero, rickets and increased traction on the sternum due to abnormalities of the diaphragm have been postulated as specific mechanisms.[2]