Actually, there are some potential genetic that can affect your cardio-vascular system. For example, 地中海貧血 (Thalassemia). I myself is a Thalassemia minor. My red blood cells are smaller. Therefore, will have a lower VO2max figure. There is noway for me to run at 4 minutes/km pace.
Also, your genes has defined your muscle fibre type as well (slow twitch or fast twitch). If you are born with a sprinter's muscle but try to run a full marathon, that is possible but you need to work twice as hard.