I know Big Love isn’t that factual about LDS a lot of the time, but one thing that confuses me and I think IS based in truth is the idea of going to the afterlife with the family you’re sealed to, right?
So if you’re married and sealed to your husband, does that mean you’re only with his family and not like your mom/dad/sisters/brothers? And then are your daughters not with you if they’re sealed to a new family? Are you only with the male line?
As a self-excommunicated Mormon, I might be able to answer this with a little clarity, but I left the church fairly early, so my experience won’t be all encompassing by any means.
The idea of being sealed with your family has 100% to do with the male line/your first (and what the church assumes should be your only) husband. The same goes for your daughters—they’re sealed to their husbands, and so on.
This gets really messy in cases of divorce, and if you’ve never been married/are gay, you’re either pressured into a family you don’t want, or are significantly and largely shunned from your religious community. This is why gay is only okay when it’s invisible: you should still be fulfilling your duty to Heavenly Father/the Church in marriage and family, whether or not you’re actually oriented that way.
In cases of second marriages, etc. from what I remember, the right to get into Heaven (which is controlled by your husband, and thus the reason to get sealed: you’re basically a piece of his baggage that he drags along on his journey to deification, and not a “god” on your own right) is controlled by the first husband unless that first sealing is annulled by the Church (and this is a GIGANTIC pain in the ass, if you even ever get it).
Without marriage, I believe women remain sealed to their fathers (sealing is typically done when you already have children, so when daughters get married, “giving her away” is actually pretty literal, and I believe a part of the closed door temple marriage ceremony still has some sort of ritual like this. But I left as a teenager, so I can’t say this for absolute certain).
And if your family has never been sealed, or you’ve been married/never been married so you’re not in someone’s sealed family, the reason you’re either pressured into it or effective ignored is that not being sealed to a man in some fashion means that you basically have next-to-no entrance into Heaven. And for a man to go into heaven/ascend is a source of shaming.
TL;DR: yes, it moves exclusively along the male line.