The common origin of technique.
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The commonality of a technique is that they all make use of biomechanics and weaknesses of the human anatomy. Where the various arts differ is in the rules, the goal, and the context that they are trained for.
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In competitions you try to win. In consensual fights you actively seek the engagement. In self-defense you try to end a dangerous situation as quickly as possible. The fight, if it cannot be avoided, is not consensual.
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While there are some common techniques, the goals and objectives are different, and that means different tactics. It also means there are methods that don’t apply universally (not everything is common). For example, if you were grappling to escape (as you would in self-defense / old school karate), then you’d seek to remain upright when throwing and not end up on the ground. So, the way in which the throws would be applied would be different. Largely the same technique, but done a little differently due to the differing goals and tactics.
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Common technique does not mean a common approach.
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Sometimes a motion will have several related applications that differ in context, yet still use the same mechanics. When compared to language, this is similar to how a word can have more than one meaning. The word itself is the same, yet the way it is used is very different because it is defined differently. For example: A circular motion may in one application be a strike, in another, it may be an evasion.
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The motion is the same, but the emphasis is different.
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Widespread throughout the martial arts is essentially the false assumption that common methods must have a common origin. In truth, common methods most often evolve independently due to common combative problems and common physiology.
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The false assumption is that any given method can only originate in one place. ie “that joint lock is from Jiu Jitsu”, or “that throw is from Judo”. The truth is that these arts developed common methods independently of each other.
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Common physiology and common problems necessitate common solutions.
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All these systems developed variations on the methods independently. The older versions of the art have these methods contained within them, although they will differ in their emphasis.
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Don’t look the wrong way through history. These similar techniques didn’t find their way into karate…… they evolved independently, are already part of old school karate, and the more modern systems came to the same conclusion. 
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NOTE: “Tegumi” 手組 (grappling hands) was the term used to describe the grappling aspect of old style karate. “Tegumi” is also used to describe an indigenous style of wrestling practiced in Okinawa.
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With thanks to Iain Abernethy
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