Is it a sin never to marry or have children?
Read Dave’s answer
Answer 1
God will judge each of us according to the desires of our hearts.[1]
If a man or woman selfishly desires, without asking God in prayer, to never marry or have children, and then follows through with their desires, then that should be considered a sin or omission, because it is almost certainly contrary to the will of God.
If a man or woman desires to marry and/or have children, but never does, because of circumstances beyond their control, their righteous desires are counted to them as righteousness, and there is no sin. Even better, their righteous desires will, at some unknown time after the trial of ones faith, be fulfilled according to the sure promises of a loving Father in Heaven.
Footnotes
[1] “According to the Desire of [Our] Hearts” - Neal A. Maxwell