Workday 108 Trivia 11-8-11: What kids don’t have.Ryan ReynoldsRyan ReynoldsPublished: November 8, 2011Share on FacebookShare on TwitterChildren don't develop these until they're at least 2-6 years old. Read more to get the answer, and use it to win cool stuff on our website!Answer: Knee caps.Source: http://www.faizani.com/news/news_2003/human_body_facts.html