No, it isn't. You could grow a dozen ferns in a controlled greenhouse environment, and every leaf of every plant will be unique. No, it isn't. No. It's because real object follow real physics, not abstract math. As you point out, growth instruction comes from DNA, not math formulae. DNA does not contain the Fibonacci sequence. The similarity to a pattern that can be described by the Fibonacci sequence is an emergent** property of physical processes, changing over time. Emergent specifically means that the information for the end result is not contained within the initial configuration. No. That is not how living things are built. They are built by enzymes, coming and going, and the resultant growth rates. The resultant shape is an emergent property; it is not contained within the blueprints. If the growth of a living thing is analogous to building a brick wall, then this is what happens: - there is no architect looking at the big picture, - there are no large scale blueprints of what the wall "should" look like. - there is no formula that shapes the wall. all there is, is - each brick contains its own set of instructions about how to place it in its position. Any given brick knows absolutely nothing about the larger structure, only its neighbors. Its instructions simply tell it how to position itself next to its neighbors. (In life, the instruction is not a formula; it is simply trail and error of what worked and produced more offspring. Leaves that don't overlap will get more sun, produce more offspring - that bit of enzyme-protein sequence gets passed on. There is no logic to the instruction; only the consequence of survival and offspring.) When enough bricks lay themselves down - each with very similar, yet very slightly different values - you will see a gently curving wall of a certain height and length. And here's the kicker: Nowhere, in the instructions of any given brick - in fact, nowhere in existence - are there instructions for building a curved wall - let alone a formula to follow. It is entirely emergent. We humans have found that, when structures get built this way, with one or more factors changing slightly with each iteration, that we can describe it with a general formula that takes into account both the constant values and the changing variables - a formula that does not exist in nature.