Hi Gino,
The 144,000 are indeed a mystery. Whilst I obviously cannot answer your question definitively, I do have some thoughts.
I lean towards these young male virgins being Yeshiva students. Orthodox and currently involved in deep study of the Torah. They are, of course, virgins. I have believed this since young 15 year old Natan was taken to heaven to receive prophecy. Although Natan was not a Yeshiva student at the time - he was young and innocent. Too young to have committed any cardinal sin.
If we Christians even had a tiny inkling of what a Yeshiva student learns and goes through - we wouldn't hesitate to identify he 144,000 as young, male students of the Torah. They devote their lives - from a very early age to the Torah. Nothing else comes close. Their lives are entirely devoted to Almighty God and His word. They are virgins - physically and spiritually.
Young Natan was not a Yeshiva student .....and he was chosen on purpose. He had no idea of the Torah or prophecy. He reported back exactly what he saw and heard. He had no bias or leaning to any particular teaching. He was innocent of all prejudice and bias. Natan had little idea of the politics and drama he was talking about. He simply reported back what he saw and heard. Natan was also obviously a virgin.
All these mysteries will soon be revealed. I cannot wait !!
God Bless you, Gino. And all the Doves.