What we know about the Montagues and their son must largely be surmised from Romeo's actions. There is not the intense dialogue from Lord and Lady Montague as there is between the Capulets and Juliet. In fact, Montague has only ten lines of dialogue in the entire play! (See link below.)
We know that Romeo does not hold the anciet animosity for the Capulets that his parents cling to. When Juliet asks him to "Deny thy father and refuse thy name," Romeo does not hesitate to respond with "Henceforth I shall never be Romeo...My name, dear saint, is hateful to myself / Because it is an enemy to thee" (2.2)
The fact that Romeo is so willing to give up his "good name" is pretty telling of his relationship with his parents. They have not given him much reason, in his opinion, to value his family ties.