The story of Nicodemus visiting Jesus in John 3 is loaded with 'Greek goodies', including plays on words that don't translate into English, and words that are ambiguous in interesting ways. Here are a few…
The first is the Greek word GENNAŌ, translated 'born'. In Greek this word refers to the entire reproductive process, and thus can refer to both the male and female roles. Thus in Matthew 1 when we read "Abraham begat Isaac", etc. etc., all of those 'begats' are this same verb. So whether to translate it into English as 'beget' or 'born' depends on context. In this passage we read Nicodemus' astonished reply "Can anyone enter their mother's womb a second time…" so clearly Nicodemus is thinking 'born', so that's why it's translated 'born' throughout this passage. However, this same verb is used later in this passage in the famous John 3:16: "For God thus AGAPÉ-loved the world, that He gave His only-born/begotten son…". I can't think of any theological implications of 'born' and 'begotten' are the same word throughout, but it does show that there is a unity of thought in Jesus' discourse here that gets lost in the translation. By the way, in first century Palestine first-born sons in particular not only inherited the characteristics of their fathers, but also their property and authority. So, metaphorically speaking, when we are 'born/begotten from above', we too take on both the characteristics and authority of God.
The next is ANŌThEN, which can be translated 'again' or 'from above'. So both "you must be born again" and "you must be born from above" are accurate. I personally like "from above" because if you're born from above, logically you've been born again, whereas being 'born again' doesn't logically imply being born from above or from anywhere else. Also, a recurring theme in the Gospel of John is 'ascending and descending', 'heavenly' vs. 'earthly' — indeed it shows up in verse 13 "no one has ascended into heaven except the one who has descended from heaven". But scholars go both ways on how to translate ANŌThEN. Better still is for you the English reader to be aware that it means both and let that inform your meditations on this passage accordingly!
Finally we have PNEUMA which means 'spirit', 'wind' and 'breath'. So in verse 6 Jesus says "…what is born of the PNEUMA (spirit) is PNEUMA (spirit)" and then continues in verse 8 with "The PNEUMA (wind) blows where it chooses…". It's a play on words!
So, to translate this passage in a way that highlights all this (hardly smooth reading!):
"Jesus answered and said to him: Truly truly I say to you, if someone not be born/begotten again/from-above, he can't see the kingdom of God.
Nicodemus says to him: How is someone able to be born/begotten being old? Is he able to enter into his mother's womb a second time and be born/begotten?
Jesus answered: Truly truly I say to you, if someone not be born/begotten from water and PNEUMA (spirit) , they can't enter into the kingdom of God. That which is born/begotten from flesh is flesh, and that which is born/begotten from PNEUMA (spirit) is PNEUMA (spirit). You should not marvel that I said to you, You must be born/begotten again/from-above. The PNEUMA (wind) blows where it wants, and you do not know whence it is coming and where it is going, thus is everyone who has been born/begotten by the PNEUMA (spirit).
Nicodemos answered and said to him: How can these things be?
Jesus answered and said to him: You are the teacher of Israel and you do not know these things? Truly truly I say to you that what we have known we speak and what we have seen we testify, and our testimony you do not accept. If I told the earthly to you, and you do not believe, how will you believe if I tell the heavenly to you? And no one has gone up into heaven except the one having come down from heaven, the son of man. And just as Moses lifted up the snake in the wilderness, thus must the son of man to be lifted up, so that everyone believing in him may be having eternal life. For God thus AGAPÉ-loved the world: that he gave his uniquely-born/begotten son, that everyone believing in him not perish but be having eternal life."
Whew, there's a lot there!