Well the thing is that doesn't neccessarily disprove it either - if the only births allowed are male then that may be why it is <2 - if the practice is widespre

Well the thing is that doesn't neccessarily disprove it either - if the only births allowed are male then that may be why it is <2 - if the practice is widespread enough it won't even stand out statistically - the ones that don't would and even then there are many other confounding variables like wealth level and density.