There seemingly are some environmental factors out there diluting testosterone levels (certain plastic seem like a risk, for instance), but pubescent boys are not taking contraceptive. That's a weird specific bogeyman to call out.

Don't downplay the influence of interracial mixing in the Americas, where I will perhaps incorrectly assume you live. Large amounts of body hair are not a universal male trait. Europeans and Mediterraneans are much hairier than Native Americans. If your ancestors were mostly on one side of that, then sure, they were hairier. Many of my more distant ancestors had no body hair at all.

You may notice a tradeoff here, as the same sensitivity to DHT in your hair follicles that causes facial hair to proliferate also causes male pattern baldness, and Europeans go bald much more often.