Back when Richard III of England's grave was discovered, a paper published in Nature Communications reported that while his identity was confirmed through a direct-female descendent of his sister,
Y-chromosome haplotypes from male-line relatives and the remains do not match, which could be attributed to a false-paternity event occurring in any of the intervening generations.
News articles at the time, including a BBC article and a Guardian article, worked this into a bombshell: The Tudors might be illegitimate!
The anonymous male line relatives all descended from John of Gaunt, who shared with Richard a direct-male link to Edward III. So assuming the tests were accurate and at least one of the relatives had legitimate lineage (both nontrivial assumptions!), then either John of Gaunt or Richard III (or both) did not descend from Edward III through the male line. The former possibility is significant because that would mean the Tudors had a much less legitimate claim than believed. The latter is also significant because that would mean Richard's brother Edward IV was likely also illegitimate.
Anyway, since then there's seemingly been no developments or follow-ups to these bold claims. Most of what I could find on the topic has been about assuring folks that the Queen's legal status is secure in any event, e.g.:
What are the immediate legal effects of rendering a royal branch illegitimate?
But I'm still curious for curiosity's sake. In the 6 years since the paper, has there been any further investigation into why Richard's DNA didn't match his living relatives?