Well, I say that you are really smart. Mercury is in Cancer in the XII house but a 6° degrees from the 1st, so it influences both but more the 1st since thats the house Mercury is entering, using classical astrology we have a Mercury in Cancer in its own decanate and exalted by a Jupiter in Libra, place where Mercury has its own nocturnal triplicity (since the chart is nocturnal by being the Sun in the 1st house) so counting your Mercury will have 4 points, which is good.
And also could mean that your brothers have a good relationship with your dad or family in general because Mercury ruler of your 3rd house in Virgo in mutual reception with Jupiter in Libra, ruler of your 6th house in Sagittarius, since also being the 6th house in derived houses, the house of the family of the brother (the 4th of the 3rd)