It's always been a thorny question, and frankly, the answer Jesus gave does little to anwer it, unless one believes that Jesus is referring only to life in heaven:
24 “Teacher,” they said, “Moses told us that if a man dies without having children, his brother must marry the widow and have children for him. 25 Now there were seven brothers among us. The first one married and died, and since he had no children, he left his wife to his brother. 26 The same thing happened to the second and third brother, right on down to the seventh. 27 Finally, the woman died. 28 Now then, at the resurrection, whose wife will she be of the seven, since all of them were married to her?”
" 29 Jesus replied, “You are in error because you do not know the Scriptures or the power of God. 30 At the resurrection people will neither marry nor be given in marriage; they will be like the angels in heaven. 31 But about the resurrection of the dead—have you not read what God said to you, 32 ‘I am the God of Abraham, the God of Isaac, and the God of Jacob’ a ? He is not the God of the dead but of the living.”
It seems to me that those who asked the question were thinking of earth-related eventualities while Jesus seems to be speaking of heaven-related eventualities. Otherwise, his reply just doesn't make sense, unless, as some say (including the WTS), that earth-dwelling resurrected ones somehow become 'as angels' with no desire to marry. But even so, it's a problematic conclusion to reach, as some of the comments to this thread have already highlighted.
