My wife & I have an 18-year-old son. He started university in September, studying medicine. There he met this 41-year-old man - a classmate, and they became really good friends. This man has just started university now at this age because apparently he was born poor and in the first half of his life was focused on making money, but medicine is a dream of his. Son has always been an introverted, shy, socially awkward kid with little friends, but now goes out often. Honestly my wife & I are uncomfortable, and we can’t help but side eye the dude.
As a 40 something man, I’ve found that my friend groups tend to shift by life stage more than age.
We have friends that are 10-15 years older than us because our kids are the same age, and we have friends that are 10-15 years younger than us because we have overlapping hobbies or work together.
At this point in my life, I don’t even bother finding out someone’s age until I’d consider them friends, because it doesn’t matter if we’ve found something we connect over.