Thanks to all who left comments on my previous post. This discussion has been very useful and led me to adjust my views. Here’s how I would formulate the issues now:
(1) ‘Phenotype’ is determined jointly by (i) genetically stored information, (ii) culturally stored information, and (iii) the environment. It doesn’t make sense to speak separately of ‘phenotype resulting from genetic influences’ or ‘phenotype resulting from cultural influences.’ Culture can affect the morphology (foot binding in China) and skin coloration (tattoos). Genes affect cultural behaviors (e.g., political leanings to liberalism versus conservatism). Different traits are affected by different mixtures of genes, culture, and environment, but there are no sharp boundaries.
(2) Genetic information stored within an organism is its genotype, but it is also important to know how much genetic variability there is in a population.
(3) Cultural information can be stored in a variety of media. Initially it was just inside people’s heads, later texts and images became very important, and today (or in the very near future) most of cultural information will reside in the electronic form. It doesn’t seem to matter how it is stored. People who want to call cultural information ‘cultural genotype’ are welcome to it, but I prefer not to do it, because:
(i) culture, unlike genes, can be stored in a variety of media
(ii) what’s important is not cultural information stored in a single person (the most direct analog of the genotype), but the collective store of culture. So, if you want to push the analogy, human groups have cultural genotype, not human individuals
(iii) there are several other differences between genetic and cultural kinds of information that make this analogy not very useful (as detailed in my previous post)