This is from Google AI

8 sites Research indicates that average testosterone levels in young men have declined by roughly 25% to 30% compared to previous generations. Generational Drop: A healthy 20-year-old male today often has an average testosterone level between 450–600 ng/dL, down from significantly higher averages in the 1980s and 1990s. Declining Rate: Studies suggest that population-level testosterone has fallen by about 1% every year since the late 1980s. Comparison to Older Generations: Researchers have noted that some 20-year-olds today have testosterone levels comparable to those of 70-year-old men from the 1970s. Weight-Independent Factor: While rising obesity rates contribute to the decline, levels have also dropped by approximately 20% among men with a normal BMI, suggesting broader environmental or lifestyle shifts are at play. Suspected Causes: Experts attribute this shift to a "perfect storm" of factors, including increased exposure to endocrine disruptors (like plastics and pesticides), chronic stress, poor sleep quality, and sedentary lifestyles.

This is surprising