Actually, after years of training people in martial arts and other self-defense disciplines, there are some caveats there. The proportional strength ratio between arms and legs is 3 to 1 for women, 2 to 1 for men. That actually doesn't mean that a 130 pound woman's legs are stronger than a 130 pound man's legs.... and most men weigh a lot more than 130.
Kicking for the nads is a part of any fighting/self-defense toolbox, but it is also often overrated. The nads are not an "off-button". Contrary to myth, the testicles are a pretty small target, and a direct and square-angle impact is needed to really incapacitate a determined attacker. Also, men are aware of the vulnerability of their testicles and tend to guard them instinctively. Typical reactions include the hips moving back as the hands come down to block. This tends to make a nad-shot even more difficult, unless it is done by surprise or slipped in when the opponent is distracted. I actually recommend kicking the knees as a primary target, and advise using a knee strike or hand strike for the nads for greater accuracy. Also, I view nad-shots as more of a distraction (to enable a follow-up strike) because of the difficulty in getting a solid shot in against an aware opponent. Didn't mean to derail, this is one of my "lecture" buttons....