Okay, first off: Squeeeeeeeeeeeeeeeeeee!!!
Secondly: I'm an adult by pretty much any standard, and I have always found coffee completely undrinkable. I prefer tea (Lapsang Souchong is a favourite, as well as Earl Grey), or soft drinks. I have known people my own age who refuse to drink any hot drink, and people significantly younger who take their coffee black and strong enough to permanently mark stainless steel.
Being able to tolerate a particular beverage is not a good measurement for adulthood.