In most societies 18 year olds are seen to just be starting their life. Is it wrong for a 40 year old guy and an 18 year old girl to date if she's still
I gave a lot of examples above to really drive the point home, but there is also a good trick you can use to remind yourself when to hyphenate years old and
Hyphenate year old if the phrase precedes a noun that it is modifying. Grammarly can save you from misspellings, grammatical and punctuation mistakes,