Star Trek: 10 Things You Didn’t Know About The Duras Sisters
1. A Question Not Answered
Having done a minor detour to DS9 after their defeat in the Klingon civil war, the Duras Sisters would return to The Next Generation in season seven's Firstborn.
K'Mtar (Future Alexander) arrives to teach his younger self the Klingon Way in a bid to save his father's life further down the timeline.
The twist is only given away when a knife used in an attempted assassination features the House of Duras crest. It includes a symbol representing Lursa's son. The symbols also show Ja'rod, Lursa, and B'Etor with the notable absence of Duras, who is replaced by the as-yet unborn child.
At this point Lursa had only just discovered that she was pregnant and had told no one but B'Etor. It's an unsettling moment in hindsight since Generations doesn't reveal what happened to the child and there has been no canon reference to Lursa's offspring. Star Trek Online would however expand on this, with that son surviving into the 25th Century and having taken the name of his grandfather, Ja'rod.
Even taking that into account, there has been no identification of the father. One might guess it would be a member of their crew from the ill-fated Bird-of-Prey since the sisters are fugitives at this point in the timeline.