瑜伽論記 6.142

6.142

下釋中，先反釋，所以者何？若法異相，俱有而轉乃至種種流轉者，此釋種姓，依身處定，若彼種姓與所依身，有別體性，俱時而轉，可便得言；或依此身、或依餘身，即無別體，故不得有，此身種姓，墮餘身中。

In the explanation below, it first explains by the reverse: "Why is that? If a dharma had a distinct mark and evolved co-existently... up to... evolving in various ways..." This explains that the gotra is fixed in its locus in the body; if that gotra and the body on which it relies had distinct essential natures and evolved at the same time, one could well say that it relies either on this body or on another body; but since they lack distinct entities, it is impossible for the gotra of this body to fall into another body.