They believed that when the body died so did the soul. Since there was no mention of the dead being brought back to life in the first five books of the Bible, they concluded that there was no such thing. They were not the least bit open to Jesus' teachings. In fact, they were trying to trap him. They wanted to embarrass him--to discredit him and expose him as a fraud.
They brought Jesus a complex riddle. If a man married and died before he had any children, it was the custom of the day for his next oldest brother to marry his widow. In their riddle the Sadducees had the widow marry a man who then died, then his next oldest brother, who died, then the next, until she had married and buried seven brothers. "In the resurrection," they asked Jesus, "whose wife will the woman be?" Obviously, the Sadducees hadn't asked this question for edification. They didn't even believe in a resurrection!
The Sadducees' question was a test. It was a trap. Jesus, though, saw this as an opportunity to set the record straight. In heaven, he explained in verse 36, there is no need for marriage, "because they are like angels and are children of God."
I believe, in heaven, we will know our family and friends, but heaven will be more wonderful than our human relationships.