What?!?! No. Blood, broadly, isn’t the same thing as red blood cells. RBCs are just a component of blood. RBCs carry O2 and CO2. Sometimes CO if you’re unlucky or a smoker. There’s a fuck ton of other shit floating around in what we call blood.

A simple and very basic biology class can answer all the questions you have. That’s why our education system is so depressing. Upstream body parts aren’t a thing.

Our DNA is equivalent to a computer program that tells our body how to interact with everything in our environment. The only problem is that we don’t know how to decipher it.

Great examples are the presence of the BRCA gene and alpha-1 antitrypsin deficiency. With BRCA you’re gonna get Brest cancer no matter what. With alpha-1 you’ll get liver or lung or gut cancer but you can actually determine the age range that an alpha-1 will cause someone cancer.

I recommend Khan academy, elsevier, and courses for free biology courses. Physiology and biochemistry also address this topic.