Biochemical cascades in just one cell are very complex, and involve very large molecules. They are triggered by changes in solutions of these very large molecules, heat, and immuno cells. Tissue consists of billions of cells. These are "just" chemical reactions which we still haven't come close to getting right, such as the right dose of blood thinners to prevent clots from afib while not causing brain bleeds, or the right dose of statins that reverse artery plaques while not destroying your liver or the right dose of beta blockers that lower blood pressure without diluting your kidneys.
Gene space is extremely large, close to a cosmic scale. At first genes were only thought to play a role in cell division. Then came gene expression and transcription inside and outside the cell, such as protein receptors and secretion. It is very likely genetic mutations do not rely on "just" chemistry and take into account quantum effects. Despite mapping the billions of genes required and structuring them all the right way, you still get unexpected runaway mutations, because genetic molecule outsides do not represent the insides, it's impossible to determine, and impossible to configure.
Genetic molecules may not exhibit quantum behavior. Likely they do regards to genetic mutations. But neurons certainly do, in regards to their chemical and electrical synapses. I have heart disease. 10 months out of the year I'm barely consciousness. However my family members say I'm still in there somewhere. Compare this to my heart disease is cured, but family members fail to recognize me anymore, adamantly agree across the board I'm not me and now won't have anything to do with me. With mice, you can kill them by the thousands until you get one that glows in the dark or has a human ear growing out it's back. You're left with an incredibly large set of genetic and neural data you will never fully understand, never know its complete, and never know if it has been recorded correctly as that one mouse's body decomposes, and then dump it all in someone else's lap and ask for more money and more privileges to do this to everyone in the world.
Science is still very incomplete and what it needs is often directly opposed by the legitimate needs of people, such as not being horribly poisoned. It's still very much trial and error: "Hey, this guy got by with it. Let's try it on someone who's dying. What have we got to loose"? And also opportunity, as in "the Earth will experience an interference pattern of gravity waves as two neutron stars collide in front of a series of black holes acting as a divider. Get the data." Science still involves much hope, as in, even when you lack opportunity, rules of decency still apply.