Flounder
Regular
So biologically, the Minbari species was never "diluted." But of course he did pass his genetics on, which is how the triluminary can pick up his descendants.
This must could mean that our DNA have similar characteristics. You see, the DNA is what instructs the construction of the cells in our bodies. If Valen had Minbari children with Catherine, both their DNA had to be transformed in the chrysalis as well, so that it would build a Minbari body. Perhaps the triluminary picked up on a specific genetic remnant (inactive DNA) that came from the Sinclair family? And that part had to be kept as it was. Thus, human and Minbary DNA had to have a certain degree of compatibility in the first place.