One of the hardest of doctrines for us is the doctrine of the family and the promises made concerning posterity. We know that the members of the church were the Lord's most faithful spirits, but we don't want to admit that means that not all spirits in the premortal life were equally faithful. We want to take the powers of the waters of life out of God's hands, and use modern medical means to specify exactly when and how many children we will accept. We want to take the power to ourselves, but we don't want to face the spiritual consequences I think it is because we are spoiled. In our socieity we are used to thinking that we always deserve the best, and if we don't choose the best a first, we shouldn't be stuck with that which isn't. For instance, suppose a woman has a child out of wedlock, and then later repents. Can the Lord send one of his most great and noble ones to be born as that child, or will he send someone whose spiritual promises in the premortal life were not at the foremost? He cannot send one of his great and noble ones into that situation. Now that goes horribly against our thinking. We think that if she repents then the Lord should send her a better spirit child because he knew in advance that she would repent. But we don't gain spiritual blessings in advance and not all blessings can be gained in retrospect. It really isn't any different that if she chose to marry a horrible man, and is then converted to the gospel. There is nothing in that conversion that changes the fact that she is married to a horrible man. Now the fact that she has repented offers opporunities to that horrible man, or to that child, but there are consequences of our actions, and the most sacred choices can have the most enduring consequences.
If we respect the Lord in the sacred choices we find blessings beyond our greatest expectations. If we do not do so we find disappointments that are beyond our greatest expectations.
The choices of intimacy have an ability to grow into something much larger. They are the power of creation and we need to watch out for what we choose to create through them. If we choose to ignore the great creators commands, then we may find that we have spouted a branch through marriage to or to children that will be a rebellious branch. As with any of Gods children, it may be that with great effort they can be swayed, but the branch that was PLANTED in that action is not a pleasant one and it will grown and begat more posterity after its likeness - if it is not swayed it will grow into a tree with wild fruit.
And if we will instead treat the ability to procreate with the utmost respect, not damming up the waters or life when married, getting married under the covenant of Abraham so that the lord can send us posterity through our generations that will bless all the nations of the earth, and whose hearts will turn to their fathers to in turn bless us long after our death, then we have planted a good tree that can grow into something wonderful.
So we must be very careful how we respect the waters of life, as they have the capacity to grwo into a tree that mimics the source from which they sprang.
Now there is more to this doctrine. After all the disciples did ask whether the man sinned or his parents sinned that he was born blind. The disciples did know that premortal choices and mortal choices of parents can have consequences for children. But the answer was neither, but so that the glory of God could be manifest in Christ healing him. And who can argue with that as being a coveted blessing, to be one who Christ would heal and thereby show forth his power in. It sounds as if the man knew of this honor the premortaity just as surely as the man who saw Christ as a baby in the temple already knew in mortality that he would see the Messiah before he died.
We want to make the Abrahamic covenant of sealing in the temple, but we don't want to face the fact that if we intentionally choose to violate the covenant to multiply and replenish the earth, then we necessarily lose the accompanying blessing that through our posterity all the earth will be blessed, i.e. we lose the blessing that the Lord will send us spirit children that were foreordained to bless all the earth.
Yes, we can repent, but the gift of his choicest spirit children as posterity is bequeathed by covenant, and not in retrospect.