|Spoiler Inside: Solution to Puzzle||SelectShow>|
Because all of the females are younger than all of the males with one-syllable names and Lee is the youngest, Lee is female.
Kathy, Lee, and Nellie are all younger than both of Mike and Pete.
If Peter is older than exactly three people, Kathy is the second-youngest and Nellie must be third-youngest. This leaves Owen as second-oldest which violates a clue. Thus, Peter is older than four (is second-oldest), and Kathy is third-youngest. Owen is third-oldest. Nellie is second-youngest.
The order from youngest to oldest is Lee – Nellie – Kathy – Owen – Pete – Mike. Lee is female.