This definitional obscurity has other conceptual downsides as well that begin to tip the idea that ‘memes replicate‘ into the realm of unfalsifiability. Let’s return to the biological domain: here, two organisms can have identical sets of genes, yet display different phenotypes, as their genetic relatedness is a separate concept from their phenotypic relatedness. The reverse can also hold: two organisms can have phenotypically similar traits – like wings – despite not inheriting that trait from a genetic common ancestor (think bats and pigeons). What these examples tell us is that phenotypic resemblance – or lack thereof – is not necessarily a good cue for determining biological relatedness. In the case of memes, there is no such conceptual dividing line using parallel concepts: the phenotype of a meme is its genotype. This makes it very difficult to do things like measure relatedness between memes or determine if they have a common ancestor. To make this example more concrete, imagine you have come up with a great idea (or a truly terrible one; the example works regardless of quality). When you share this idea with your friend, your friend appears stunned, for just the other day they had precisely the same idea.