The mother of Brutus

[Gladius Hispaniensis]

Ave

I was reading Penguin Classics translation of Sallust's "Jugurthine War/The Conspiracy of Catiline" and when the author mentions an associate of Catiline named Sempronia there is a footnote saying she is the mother of the Brutus who was one of Caesar's assassins.
I wonder how factual that is because AFAIK the mother of Brutus was actually Servilia who was reputed to be Caesar's mistress - or are Sempronia and Servilia the same person?
Would appreciate any input.

[Nathan Ross]

There were two assassins of Caesar called Brutus, confusingly - Marcus Junius Brutus (son of Servilia), and Decimus Junius Brutus (son of Sempronia).

Caesar did indeed have an affair with Servilia, when he was very young. I think Syme (Roman Revolution) suggested that D Brutus was more likely to have been Caesar's son, of the two. Probably neither were though...