I think that at the time COT aired, this was a plot hole. It had not yet been established that Trill and Klingons can't have kids (easily) so all we know is that the two get married and yada yada they have descendants. The implication is therefore that their descendants come from their marriage so anyone on Gaia with Trill DNA would have equal parts Klingon and vice versa since that was the original combination. IF there were another Trill or Klingon in the crew then through subsequent matings with those descendants there could be some strengthening of one genome over another. Like, if Worf and Dax had two kids, one married a Trill and the other marries a Klingon then the two species would diverge. And though there is a possibility of there being another Trill, we know Worf was the only Klingon.