This suggests its more environmental, chemical, diet-based, etc.
My 12" ultra-portable sits on my desk at home/office. When commuting if I'm using it, it will sit on my backpack on my lap.
My 17" laptop that is heavier than my desktop, stays on the kitchen table.
 The dirt: https://www.ncbi.nlm.nih.gov/pubmed/12419695
>In contrast, no significant decline was seen in South America, Asia and Africa.
Presumably on average these regions are also seeing similar temperature increases. I'd think that whatever the cause is, it's not something that is affecting people on a global scale.
Also, temperature-dependent sex determination is only seen in a few species, and not in mammals as far as I know: https://en.wikipedia.org/wiki/Temperature-dependent_sex_dete...