#Credence Barebone is probably Voldemort's mother.
Yeah, you got it right. I think Credence is a woman. And Voltemort is her son.
Here is my explanation:
1. Ezra Miller is a great actor who could play both: male and female roles. There are pictures of him, disguised as a woman.
2. Name: Credence, Chastity and Modesty are certainly not the real names of the children, but given by their adoptive mother Mary Barebone. Credence is a rare name. It can be used for a boy, or for a girl.
3. Here is what we know about Voldemort's mother, Merope Riddle (Gaunt): She is the daughter of Marvolo Gaunt, descendant of Salazar Slytherin. We don't know what happened to her mother. She was raised by her abusive father. The family was very, very poor.
She probably never attended a wizarding school. Her father and brother abused her, and called her Squib, so her magic was suppressed. Like with Credence.
Her father and brother were both arrested in 1925, and she took the opportunity to run away with a wealthy local Muggle Tom Riddle, after she has bewitched him, with a Love Potion. Once released from the prison, her father was angry about that, because Gaunts were accepting only pure blood marriages. So, Marope and her husband remain hidden in London.
She eventually became pregnant and stop giving him Love Potions, in hope that he already fall in love with her. She was wrong, however, and he instantly left her.
We know very little, what happened after that. Merope had no money, so she had to sell her Slytherin locket, in order to survive. We also know, that she gave birth to Tom Riddle aka Lord Voldemort, on 31 December, 1926 at Wool's Orphanage. Which is, about a month or two after the events described in „Fantastic Beasts and Where to Find Them“. But her life during the pregnancy remained rather unknown – until now.
Perhaps she sold her valuable locket, in order to buy a ticket for New York? She was still hiding from her father.
Perhaps she wanted to start a new life there, but because the lack of money ended up with Mary Barebone?
Or was she searching for her biological mother, just to find out, that her mother started a new life as Mary Barebone, the fanatical leader of the Second Salom? This wouldn't come as a surprise, since we know that in Potterverse, witch hunter are often witches themselves. And after being married to abusive Marvolo Gaunt, she perhaps start hating wizards and witches. Of course, this is just a theory. Mary could also be some aunt, or random person.
upload ithatever the case, Merope Riddle aka Credence, had to hide her pregnancy, for obvious reasons. Her adoptive mother was, after all, a woman who named her daughter „Chastity“. We can't know, why she decided to act as a boy. But probably the suppressed magic is the metaphor for suppressed femininity (among other things).
4. Credence went mad, after Grindelwald called him / her Squib. This is an important point. Credence was angry on many occasions, and she had many reasons to be. But this time it was far worse. She also said something like „Perhaps I don't want to control it anymore“. We know, and I already repeated it above, that her father and brother always called her Squib, when abusing her. Was this a hint?
5. Here is another hint: Grindelwald told Credence, that he is searching a child, not older than ten. Little he knew, that that child was not even born yet, and that the mother was standing right in front of him.
6. Credence was supposed to have very, very powerful magic inside her, otherwise she wouldn't survive as an obscurial for so long. How many so powerful wizards we know? Dumbledore, Grindelwald and Voldemort. There is no obvious connection between Credence and the former two, but the latter was born, very shortly after those events. So there has to be some connection to him.
7. We know that Credence survived the attack, and we also know (deleted scene) that she left New York, with the same ship as Newt Scamander. We also know, that Newt published his book „Fantastic Beasts and Where to Find Them“ in 1927. I think, we can assume that he published the book in London, or at least somewhere in tyhe Europe. Following this trace, we can say that Credence set out for London. And she did so, shortly before Voldemort was born in London.
8. Merope Riddle / Credence died right after she gave birth to her child. It was never told, what the actual cause of her death was. I think we can assume, that she died because of the attack in New York, or she was not able to survive as an obscurial anymore.
9. Outward appearance: Merope is described as follows: „when Harry first saw her in a memory, he still thought of her as the most defeated-looking person he had ever seen.“ Sounds a lot like Credence, eh? Also, it's stated that she is not a beauty.
10. Age: Rowling loves numbers. Merope was about 19 years old, when she gave birth to Voldemort. The new franchise should cover a time period of 19 years. Cursed child is set 19 years after the final Harry Potter book, etc.
Rowling, you are a genius!
Sorry for my mistakes, English is not my native language. :)
Do you like my theory, and do you have more hints?