There are some arguments that I've come across in some major fitness forums, like Bodybuilding.com, where some members don't believe human bodies being made up of three different somatotypes (Ectomorph, Mesomorph, & Endomorph).  According to the National Strength Professionals Association, they say "Someone that is an ectomorph (thin framed) with a high level of neurological efficiency will likely be someone who is much stronger than he or she appears to be. Although he/she will not have a large amount of muscle tissue, they will be able to recruit more muscle fibers in a given muscle(s) than someone who may have more muscle mass but has a lower neurological efficiency. This person, however, will likely never develop very large muscles regardless of their training protocol because their somatotype won’t permit it. On the other hand, someone with high levels of testosterone will typically be a mesomorph because testosterone is the primary hormone responsible for muscle growth".

 

What they're saying is that ectomorphs won't have nearly as much muscle mass as let's say a classic mesomorph, but that does not mean that the mesomorph will necessarily be stronger than the ectomorph. Ectomorph somatotype muscle fibers have the ability to recruit more muscle fibers in a muscle to produce more "work". So if you give the ectomorph and mesomorph the same training routine, they're most likely both end up with similar strengths, however their muscle sizes will be night and day in comparison. 

 

So they answer is No. Just because you're an ectomorph, it does not mean you're going to be weak forever. With the proper training program and superb nutrition, you can be just as strong as a mesomorph. The only down side is that the mesomorph will most likely have larger/more muscle mass. But don't worry, because you have the natural ability to be leaner.