In John 3:3 (above) is a term that is unique to Christianity and is not well understood even by those have been γεννηθῇ ἄνωθεν. The word translated above as “again” is ἄνωθεν or anōthen, which is comprised of ἄνω or anō, “above, upwards,” and the suffix θεν or then, which denotes “from.”
“The most significant use of anōthen occurs in Jn. 3:3, 7 when Jesus tells Nicodemus that he must be “born again” (or does it mean “born from above”?). We really do not need to choose between these two options, for when we are born from above (i.e. born of the Spirit of God), we experience rebirth (i.e. we are born again). The ambiguity in the word beautifully covers both concepts.” – Mounce’s Complete Expository Dictionary of Old & New Testament Words, page 274.
The word translated as “born” is γεννηθῇ the aorist tense, subjunctive mood, passive voice form of γεννάω or gennaō. We get our English words generation and genetic from this word. Literally it speaks of men begetting, but in the metaphorical sense we find its usage in passages like John 3:3 in which God is begetting in a spiritual sense. This consists in regeneration, sanctifying, quickening anew, and ennobling the powers of the natural man by imparting to him a new life and a spirit in Christ (1 John 5:1). That is what it means to be “born of God” (1 John 3:9) and being the “sons of God” (Romans 8:14).