The average number of sexual partners has changed considerably over the decades. Baby boomers (1946-1964) report an average of 11 partners, while Generation X (1965-1980) has an average of 10 partners. Millennials (1981-1996) have a lower average of 8 partners. The lower average number of sexual partners could lead to bowel cancer. Joking aside. I would suggest that the world has become a bitter place. Water quality, pollution, microplastics, air quality, factory farming (meat production in general, drug distribution, multi-resistant germs). Average meat consumption per day is rising. Everything is getting worse because humans are causing climate change, suffering of living beings and nature and refusing to change the status quo.

Might be true, but I don't think malnutrition, sedentary lifestyle etc have peaked in the 70s.

If these factors are perfectly controlled for, maybe you're right. It would be stupid for me to further engage in discussion about it though, without having read science about this.

There are other things we know about though, for example an increase in microplastics intake.

Plus do not forget, the article said the "damage" happens in the first 10 years of a child's life. So people born in the 70s are also seeing an increase in colon cancer.

BTW, for my main comment, I am probably in the top 15% of age distribution of people commenting here.