Who neither marry nor are given in marriage means they are single, they are not married and they are not engaged to anyone to be married. No where in the bible does it say the angels are gender-less but to the contrary it indirectly says they are all male. Genesis 6:4 specifically says they married the daughters of men, or Adam. But they were not given permission by God to do so but being of free will they did anyway. The angels who are in heaven did not but there is a possibility that God has a plan for them as well, to have wives and children and families, at the proper time. There is a need for procreation into eternity, to fill the vast and endless universe and to fulfill the prophetic saying, "And of the increase of His government there will be no end".
Our marriages of the flesh will no longer be binding, as a covenant ends at the death of either one. Our marriage in the kingdom will be with that perfected and holy man or woman who will be a different being altogether, we will be like Christ, physical and spiritual. This is also why He didn't marry, there wasn't a woman compatible with Him physically or spiritually.
Beware of the people and the scientist and whoever else comes along, and they will, that claim they now know what happened in our past and where we came from, all you have to do is watch the History Channel. I believe that will be the big lie, the great deception that God brings on the world in this end-time.