OK, I'll be honest I don't know a huge amount about Judaism so if I write anything stupid or offensive I'm sorry in advance. I was reading about "packers" earlier (I know, I know) and they come in both circumcised and uncircumcised versions and it got me wondering what (if any) position the different Jewish denominations held on it. Went down a bit of a rabbit hole and found quite a lot of Reddit threads discussing it. This comment from one the those threads summarised my question quite neatly though:
*Is the obligation [to be circumcised] on men, or on penises?
If it's on penises: Trans women who haven't had surgery require brit milah. Trans men who haven't had surgery don't require anything. Trans men who have had surgery require hatafat dam brit (unless it's possible to construct a circumcisable penis, but I don't think it is).
If it's on men: Trans women never require anything. Trans men require hatafat dam brit whether they've had surgery or not.*
www.reddit.com/r/Judaism/comments/9vhxz3/sooo_really_really_awkward_and_embarrassing/
Could only find one official position on it which was from The Rabbinical Assembly which is the international association of Conservative rabbis. They say, thankfully, that it's about the penis not the person.
www.rabbinicalassembly.org/sites/default/files/public/halakhah/teshuvot/2011-2020/transgender-halakhah.pdf
But there were lots of other really interesting points of conflict, such as who can prepare bodies for burial (both "can a transwoman prepare a women's body"?, and "who can prepare a transperson's body?"). Also issues of menstrual separation, and the mitzvah of procreation which "applies to men and not to women because of the health risks of pregnancy and labor to women. Requiring women to become pregnant would subject them to dangers to their health". Here a person was considered to be "the new gender" once a person was "living full time as the new gender, and had gone through psychological counseling, hormonal therapy, and sex reassignment surgery." It also acknowledge that trans men can become pregnant but doesn't square this with the earlier procreation clauses.
There were some interesting other issues raised on the Reddit threads, such as using the foreskin during MTF labioplasty and what difference that would make for post transition transwomen converting to Judaism. Also one OP on the threads was asking about converting with "stealth" which I assume from context means withholding the fact they transitioned from their Rabbi/ community, which prompted this reply:
*Yichud and shomer negiah are both important, and by presenting yourself as male, you could cause other Jews, and yourself, to sin. That's not okay. There's also the issue of the mechitza.
I get that you identify as male, but that's not necessarily how halacha views you (certainly not without surgery, and possibly not with). Frankly, "stealthing" would result in you disrespecting other people's boundaries, and that's not okay.*
www.reddit.com/r/Judaism/comments/9zkjjp/considering_converting_as_a_trans_man/
Finally (last bit I promise) I read this interesting article about Jewish people who transition (as opposed to trans people who convert)
www.gendertree.com/Transformed_Before_God.htm
Exerts include:
transitioning from female to male “made involvement with Judaism possible for me,” says Jerrold, a twenty-four-year-old man. “As a female, I had no connection to the religion at all. My Bat Mitzvah was a farce. I was the first girl to be allowed to read Haftorah at my shul but still wasn’t allowed to read Torah. None of it meant anything to me.” But as soon as Jerrold became a man, he felt as though he had a place in Judaism. His only awkwardness comes because he didn’t receive the upbringing and training that would have come with being raised as a male. He doesn’t know how to put on tefillin, and he only knows Haftorah trope, as opposed to Torah trope. He still feels “awkward about women’s roles,” such as the fact that women must sit on the other side of the mechitzah (the barrier that divides men from women in Orthodox synagogues). But as a man, he doesn’t feel it’s his place to raise these issues on women’s behalf.
and
there are some who regard transgenderism as a special benefit. Razi tells of one Orthodox Jew who identified as bisexual but vowed he’d “take a gun to the head” before sleeping with a man. Someone brought up the issue of transmen, and the man became excited, because that would be perfect. “Because to me he’d be a man, but to G-d he’d still be a woman, so it would be allowed!” the man said.
and
*Now that Thomas has converted from Catholicism to Judaism and from male to female, she mostly dates female-to-male transsexuals. If she chooses to have a baby with one of these transmen, most likely her partner will carry the baby in his womb. But Thomas will be the baby’s mother in every other sense. Such reverse-gender parenting situations are rare, but becoming more common in San Francisco, where transmen and transwomen sometimes date.
If the baby’s father is a gentile, will the baby be Jewish? It depends on whether you believe the mother is the person who gives birth to a child, or the child’s female parent.*
Sorry that was so long but it's been an interesting rabbit hole for me, seeing how this all fits in (or not) with religious tenants based based on binary sex. Once again, apologies if I've said anything really off the mark about Judaism that has offended anybody.