The topic of "why doesn't Traveller have Charisma, and how do I represent a boorish Noble?" comes up with some frequency in Traveller discussions.
Aside from the obvious hack of just giving characters a 7th stat for Charisma (which works fine), you can also get some mileage out of an alternate reading of the Traveller description for Social Standing (SS).
In Starter Traveller, the book says, "Those with social standing of B+ (11 or greater) are considered to be noble, and may assume their family's hereditary title." That's pretty straight forward.
But what if you decide instead that SS is how well does the character handle themselves in social situations? Assuming that SS of 11 or better is having "courtly manners" that would imply a noble background, give the player the option of actually being a noble OR having some other back story to explain their knowledge of courtly ways. It might even be possible that a high SS player came from a bloodline in exile, or that they served a noble family and the character is "passing".
Of course this is a two-edged sword. The Referee would then have to permit "fallen nobles" who has SS of less than their family due to apathy or ennui, but still maintained their title.
However, interpreting SS even more loosely allows lowborn characters who are highly charismatic to have entre into high SS situations because, though they're unlearned in manners, they have a magnetism that even nobles find charming.
I prefer this interpretation of SS. Just like having a high Education does not automatically make you a professor, having a high Social Standing ought not force a player into the nobility.
Just a thought.