Q. Lutatius Catulus (cos 102) and his son Q. Lutatius Catulus (cos 78) were both very influental politicians of the late Roman republic.
Lutatii belong into group of new families thar rose into prominence during the Punic War era. First ever Lutatius as consul was C. Lutatius Catulus at 242 and his brother Q. Lutatius Cerco followed him next year 241. It is interesting to note that elder son was Gaius and younger Quintus. Gaius’ son became consul at 220, but Quintus’ sons failed to gain highest positions. Thus we have only one Lutatius Cerco as consul ever.
We know nothing about male liniage of the consul of 102. Hoewer we know that his son was styled Q. Lutatius Q.f. Q.n. Catulus, meaning that father of the consul of 102 was Quintus. And it is safe to assume that he was Lutatius Catulus too. This grandfater Q. Lutatius Catulus clearly wasn’t of consular rank, otherwise we would have his name in the survived lists of consuls. We also know that he was married with one Popillia. Again it is quite safe to assume that this Popillia was of Popillii Leanates.
We know also about the generations of Lutatii Cerci that consul of 241 was grandfather of one Cn. Lutatius Cerco, who in turn was a father of another Cn. Lutatius Cerco and grandfater of Q. Lutatius Cerco who was a quaestor at year 90.
I propose here that father of consul of 102 was either first or second child of consul 220. Number of generations is adequate at both Cerco and Catulus lines of Lutatii to support this. Also Consul of 220 was C. Lutatius Catulus and father of consul of 102 was Q. Lutatius Catulus. So it might have been that eldest son of consul of 220 had been Gaius or it might have been that he had followed the example of his father, that Quintus was the elder and Gaius was the younger son. In any case I have included this hypothetical filiation in the following chart of the Lutatii. I have also included some other family relations into the chart. It is possible that the father of the consul of 102 was a son of brother of the consul of 220. But I think that it is not probable that he would be a generation or family line further from the consul of 220, because it seems that there were no other family lines of Lutatii than original Cerci and Catuli and there shouldn’t been room for extra generation between them. We also have no information that consul of 220 would have had a brother. That is why I think it is reasonable to assume that Q. Lutatius Catulus was a son of consul of 220.