I was always considered the skinny kid (except for a short period when I was 10-12 but that's for another entry..) and many of the sports I played, like lacrosse for example, were just not right for my body type. Being tall and skinny, my center of gravity was perfect for shorter, stockier players to lean in and topple me. My concussion record speaks to this. When I became interested in climbing, I noticed that many of the best climbers were skinny little kids! They could lift and pull their body weight with the greatest of ease. It almost wasn't fair! Small girls and boys, though they may not feel good at any sports, often take to climbing astonishingly well! It sounds crazy, but young athletes with little visible muscle mass can often out-perform super-strong looking adult men.
When it comes down to it, a beefy football player that can deadlift 350 and bench 300 will never perform as well as a young, thin, weak-looking kid when climbing. Young girls are especially good at climbing because of their natural balance and flexibility. I have seen very large, body builder men try easy routes at the gym and become very frustrated quickly. Their feet are blindly pawing at footholds, their forearms strain to keep up the additional weight of muscle unnecessary for climbing, curses and excuses come quickly. Then, a 12 year old girl will give the route a go, and dance up the wall, pressing with her feet, using her technique to ascend, calm, collected, smiling the whole time. Even more excuses are uttered by the hulk. If you have a son or daughter that seems small, week or thin for their age, and regular sports don't seem to fit, try bringing them to the rock gym, an environment where trained, enthusiastic staff will help build their skills and self esteem. You never know, your "weak" child may begin climbing at an elite level, it happens quite often!