Final answer:
Thoracopagus twins commonly share organs at the thorax, which often includes parts of the cardiovascular and gastrointestinal systems, such as a shared heart or liver.
Step-by-step explanation:
Thoracopagus twins, which are conjoined twins attached at the thorax, often share several vital organs. The specific organs shared can vary from case to case, but commonly include parts of the cardiovascular system, such as a shared heart or common pericardial sac, and occasionally parts of the gastrointestinal system, like the liver. In some instances, thoracopagus twins may also share other thoracic organs, but the extent of organ sharing is determined by the specifics of how the twins are joined.