Some teachers and practitioners of Tai Chi make a big fuss over lineage. To me lineage is unimportant if you cannot pass on the skills properly.
Passing on the art of Tai Chi properly pre-supposes a certain quality control if the notion of lineage is to be of import. Take a look at the pictures below.
The left most picture is a student who has not even learned 3 months (I think its less than 2 months). The second photo is a student of a few years learning. Looking at the pictures from left to right you can see an evolution from external to internal, from obvious to hidden, form to formlessness.
You can also see the same principle at play here. To illustrate this I have added in the model that our Single Whip posture is built on :-
When you see a consistent development then it means that a certain amount of quality control is at play here which means that the art is transmitted using a defined set of principles. In this case lineage is meaningful even if we don’t discuss lineage.
Lastly, here is another picture to show consistency. The right most picture is that of Grandmaster Dong Huling.
Can you observe the same principles at play throughout?