I have gathered a lot of proxy statistics to support the claim of generational hormone levels, and so far no one has come up with any other explanations for the correlating statistics.
Sunspot cycles have been used to create/support all kinds of pseudoscience. If you would have a direct correlation with hormone levels, then that would be interesting to see, but like I said, sunspot cycles are mainly pseudoscience.
The theory is concentrated on the Western nations for a reason, since historical generational data and especially the proxy statistics for oxytocin are available from these nations. If you have breastfeeding rate, maternal age, divorce rate, and/or alcohol consumption statistics from Mexico, I'd like to take a look at them.
Every cyclical animal species has populations that are not cyclical, but the rules/parameters are not clear yet why some are and some aren't cyclical populations.
The 80-year periodicity comes from the Strauss-Howe generational cycle, and especially from the nurture-curve, which is presumably actually an oxytocin cycle, if the proxy statistics are correct in displaying oxytocin levels. The reason for the length is yet unknown, as it is for the other cyclical animal populations, which vary from about 4 years (small rodents) to 38 years (moose).
The statistics have to be historical statistics (like they are in the theory) in order for the decades long shifts to be seen. Is there such data from Mexico?