I’m not certain about adulthood (I doubt they are equal - there are probably positives and negatives both ways), but one of my kids has a friend who is an only

I’m not certain about adulthood (I doubt they are equal - there are probably positives and negatives both ways), but one of my kids has a friend who is an only child. She spends most of her time by herself and her home is very quiet. When she first came to our house, which is constantly in commotion (in a good way), she was sort of shell shocked. She has gotten used to it over time.