I don't think 30 mins, 3 times a week of exercise is remotely close
only stretching back a few decades, my grandfather was working his own land as a subsistence farmer without much "automation"...probably doing the equivalent of three hours of CrossFit a day, basically every day. looking back at pics of him now...he was strapped, even in his late 70s (what was also known as "normal").
my genetics probably come from hundreds of generations of people who led similar lives, yours too
I achieved my "normal" body weight with a minimum of two+ hours per day, every day, of exercise...just like all of my ancestors who shaped my genes
90 mins a week is probably not enough to even slow down weight gain, we are dramatically underestimating how much exercise we need, and dramatically underestimating how much we need to clean up our diets...in 1880 basically anyone doing subsistence farming (most people) was the equivalent of a CrossFit nut with a "clean" diet...everyone