Finally, and probably best in your case, you can use youngster (s). Once more, though, this is a term that is used by older people towards younger ones. It is more used for teenagers and young adults … As per this link, the word 'kidnap' originated to denote nabbing away of a child.

Understanding the Context

When and how did kidnap come to denote nabbing of adults? Just found a link to a 1650 book that mentions I have three age groups that i want to distinguish in my research project. They are as follows: 18-45 years - i have called this group young adults 46-65 years - i have called this group adults 66