Sharon's brother is infertile. He doesn't know it, but both women do - they just let him believe that the child is secretly his.
Parodied: Leslie, Sharon and all their friends get a glimpse of their Babies Ever After future; this includes Leslie and Sharon, and they get it confirmed that the child is genetically theirs, though no straight answers as to HOW that happened.
Zig Zagged: Leslie and Sharon end up with four kids, two that are both biologically theirs, one from a sperm donation, and another obtained through adoption.
Averted: Any same-gender couples with children have adopted their kids, retained them from a divorce, used surrogate parents, etc.
Enforced: A sci-fi show is doing a 'children of the original characters' spin-off series. Except one of the characters is quite staunchly gay. A special sort of phlebotinum is invented by the writers to explain how the gay character had a baby with their partner.
Lampshaded: Leslie and Sharon have a child which is genetically both of theirs. Sharon's brother isn't sure how they managed this, and is frequently found wondering about it, but never gets more than a hand-wave by way of response.
Invoked: Leslie, being a big fan of slash fanfics, proceeds to volunteer for strange alien rituals at the drop of a hat, invokes bizarre magical genies/demi-gods, drags Sharon to any remotely magical/mysterious fertility temple she can find, and wishes really, really hard on her birthday candles in the hopes that she will 'unexpectedly' get knocked up by her same-sex significant other.
Defied: When they get to the ninety billionth magical fertility temple, Leslie finally gives up. Sharon realizes that this makes their last attempt much more likely to work and, having only gone along with the whole thing because she believed it was genuinely impossible for Leslie to succeed, she quickly swaps herself out for her brother. Who promptly gets knocked up by Leslie via magic ritual.
Discussed: Leslie and Sharon considered trying to genetically produce a child of their own in the past, but gave up that idea due to the unstable and dangerous complications involved. When their adopted son has a mild crisis of self, they tell him about their decision and explain that in the end they decided that genetics were less important than having a healthy, happy baby to raise together.
Conversed: Sharon's brother worries aloud to her that Leslie might knock her up, because even though she's a woman she's also a sorceress, and who knows what a sorceress can do?
Children with two genetic donors of the same gender face the same sort of prejudice that their parents have dealt with, labeled "freaks of nature" by self-appointed Moral Guardians. Leslie and Sharon's family become a target for violence due to their "unnatural" union.
The children are created via a failure-prone process and end up with a muddle of genetic conditions.
Reconstructed: Despite this, Leslie and Sharon work tirelessly to give their children the best life possible, and the kids manage to make some friends at school. It's implied that future generations will be more accepting, and a "Where Are They Now?" Epilogue confirms this, showing homosexual couples enjoying equal rights.
Bob only thinks he got Alexander pregnant on account of their bizarre and adventurous lifestyles and one small, misheard conversation between Alexander and their doctor.
Played For Drama: The method used to produce these special children is difficult and dangerous, and Leslie and Sharon argue about the risks. They also face opposition from so-called Moral Guardians seeking to shut down such projects, red tape from uncaring bureaucrats, and pressure from their family to give up this insane idea and settle down with "normal" significant others.