Delinquent Crawlers

So far none of my children have crawled on their knees. Why is that? I know that it is perfectly normal for little ones to crawl different ways, e.g. army crawl, slide on their bottom, etc. But all 3 of my boys have done the same thing. Of course, the jury is still out on Micah to see if he will really get up on those knees or not, but so far he's followed in his brothers' footsteps (can I say that in reference to crawling?). So, we're into the army crawl here. You know, where you slide your body forward by pulling with your arms. Luke almost looked like he was kayaking, the way he would move his arms from side to side and drag himself along. He could slither really fast! I really thought Micah was going to break the mold and crawl like other normal kids, but alas he's slithering with the best of them. Joshua and Luke both learned how to crawl on their knees the same day they started walking. We'll see if Micah will go that far in being like his big brothers!