Today, "Mama" is "Abba," Hebrew for father, and Erica's family - which includes her "Papa," Matthew Solis, and twin 5-year-old brothers - is among an increasingly visible part of the lesbian, gay, bisexual, and transgender (LGBT) community: families with a transgender parent.
A 2011 survey of 6,500 transgender and gender-nonconforming adults conducted by the National Center for Transgender Equality found more than one-third of them had children. This year's Philadelphia Family Pride conference included several panels on transgender parenting. And on Nov. 3, communities across the country celebrated the fifth annual TransParent Day.
The experiences of transgender people - an estimated 700,000 U.S. adults, according to the Williams Institute, a UCLA law school think tank focused on LGBT issues - point to a different way of thinking about maleness and femaleness as complex facets of identity that unfold over a lifetime, rather than facts declared conclusively ("It's a boy! It's a girl!") at birth. And when gender transition happens after marriage and parenthood, it tests a family's tenacity, flexibility, and love.
Growing up, Yoel recalls, "I always felt like I belonged on the boys' side of things, but I didn't see myself being a boy."
She met Matthew at Buffalo State College and was open with him about her hazy gender identity. That didn't stop him from proposing one evening, on a staircase between their two apartments. He recalls, "I created a new little subcategory in my brain" for Yoel, who loved to sing Broadway ballads and have deep conversations about the universe.
They married in 2000, in a Jewish ceremony in a Staten Island synagogue, with the bride in a white dress and the groom sporting a Pink Panther tie. Yoel gave birth to Erica, then the twins, and nursed all three children.
A decade into marriage, what Yoel called her "gender issues" weren't going away. "But having children absolutely raised the stakes for me. I kept thinking: How could I transition? How would the world react?"
After much soul-searching, and with Matthew's support, she began weekly testosterone injections in 2011.
Soon the male pronouns they'd begun using at home made sense in the wider world: Yoel's voice had deepened and his body hair had thickened. By December, he'd saved enough money and sick time for "top surgery" that cost $7,000.
Matthew never considered leaving. "I was in a couple with someone I had a very strong connection to. And in a lot of ways, we'd recognized Yoel's maleness already."
Throughout the transition, both men were frank with Erica, then 9, and her brothers. "I had years of having a mom and a dad, and it felt like everything was changing," recalled Erica, now 11. "I didn't want anyone in my class to know. I didn't want them to make fun of me."
When Yoel asked the children to start calling him "Abba," the twins were just learning to talk; for Erica, it was a deliberate shift. "I started slowly. I'd have to correct myself. But now I'm used to it."
Therapists say kids of trans parents tend to cope better with the news at a younger age, rather than during adolescence. "It's relatively easy for a kid under the age of 7 to get the concept that Daddy's a boy on the outside but a girl on the inside," says Michele Angello, a Main Line therapist who specializes in gender issues. "It's more difficult when kids are older and can think in more abstract ways."
Today, Erica's concerns are those of any sixth grader: noisy younger brothers, a tricky math assignment, the hunt for privacy in the family's small Chestnut Hill apartment. Sometimes, classmates ask Erica whether she is adopted. She answers simply: "No, my dad's transgender."
The gender journey is not always so smooth.
Tammyrae Barr, the child of an autoworker and a deli clerk, followed the expected life path for a boy: sports and college, marriage and family.
Always, a part of him felt out of sync. When he eyed a cheerleader, he wasn't thinking, "I'd like to date her." He was thinking, "I want to be her."
For years, Barr tried to suppress such thoughts. The duplicity strained his marriage, but what hurt more, Barr said, was feeling the distance grow between him and his two sons.
When the oldest was 13, Barr finally shared his secret. "Aren't you the one who always taught me to be yourself?" Barr remembers his son asking. "I said yes. And he said, 'Then shouldn't you just do this?' "
The truth cost Barr her marriage; the couple separated in early 2010 and later divorced.
By the end of that year, Barr was, as she puts it, "living her authentic self" - a woman at work, where she designs mass-transit systems, at home, and in public. Her sons, now 19 and 16, typically introduce her with, "This is my dad. She's an engineer."
Sherman Leis, a Bala Cynwyd plastic surgeon who has performed gender-transition surgery on more than 2,000 people since 2005, says the rate of divorce among trans adults is about the same as that of the general population. The 2011 transgender survey supports his observations: About half of intimate relationships survived the transgender partner's "coming out" or transition.
"In some cases, a partner will say, 'I married him or her for better or for worse,' " says Kyle Schultz, staff therapist at Philadelphia's Council for Relationships. They say, " 'What I love is not that she is male or female. It is that he is gentle . . . kind . . . a good parent.' "
Angello, the Main Line therapist, says the better a parent has hidden his or her true gender identity, the harder time the children have accepting the new reality. "They'll think, 'If my dad was so good at lying to me, do we even have a relationship at all?' "
Patience, she says, is key. "You have to give the kid the ability to say, 'I don't feel comfortable with you showing up at the soccer game as a woman quite yet.' "
Even if family members embrace a trans man or woman's identity, the world may not. In the transgender survey, 63 percent reported experiencing bias in employment, housing, school, health care, or other arenas.
Jake Pyne, a Canadian researcher who has studied transgender families, says the kids of trans parents may struggle with discrimination and the pressure to be perfect "poster children" for the LGBT community. But they also learn authenticity, courage, and "the ability to question the limitations we are taught." "Families can really come out on the other side of this," he says. And when they do, they demonstrate the paradox of gender, the tricky knot of biology and culture we are still learning to untangle: that gender is both essential - key to a person's sense of him or herself - and irrelevant.
On a weeknight at the Solis apartment, the twins pepper a visitor with questions while Erica curls up in a corner, reading. All three kids speak English, Spanish, and Hebrew, moving fluidly among languages as they gather for a snack of tea and toasted pumpkin seeds.
The Solises are religiously observant, wearing yarmulkes at the table and attending services each Saturday at the Germantown Jewish Centre. They also celebrate "T Day," May 2, the anniversary of the night before Yoel's first testosterone injection. The following day is Erica's birthday. She likes the confluence because it means sweets - lemon meringue pie or Abba's root beer cake - two days in a row.
The twins barely recall having a mother. "Occasionally, they will say, 'You used to be Mama,' " Yoel notes, "and I'll say, 'Yep.' "
Even for Erica, the present is more vivid than the past. "I really don't remember much about what it's like to have a mom and a dad," she says with a shrug. "This is normal to me."
Yoel smiles. "Erica's not embarrassed because we're gay; she's not embarrassed because I'm trans. She's embarrassed because we're nerds."
His daughter, engrossed in a book of cupcake recipes, rolls her eyes.
Anndee Hochman can be reached at email@example.com.