President Barack Obama's other Supreme Court pick, Justice Elena Kagan, has never married and has no children.
Chief Justice John Roberts and his wife Jane were both 41 when they married. Having children was always a goal, and four years later they adopted a daughter and a son, who were introduced to the nation when Roberts was nominated to the court in 2005.
Thomas has a son, Jamal, from his first marriage. But his marriage to Virginia Lamp Thomas, whom he wed in 1987, has not produced children. The pair concentrated on raising Jamal, and later took in Thomas's great-nephew, Mark Martin.
To Cherlin, who supports same-sex marriage, such examples render the procreation arguments "at least a century out of date."
"Can the argument be that the way the chief justice had children is somehow second-class?" Cherlin asked.
But another marriage scholar, Ryan Anderson of the Heritage Foundation, said 41 states see the value in restricting marriage to heterosexual couples.
Allowing same-sex couples to wed does not "simply expand the existing understanding of marriage," he said.
Instead, "it rejects the anthropological truth that marriage is based on the complementarity of man and woman, the biological fact that reproduction depends on a man and a woman, and the social reality that children need a mother and a father."
Those who discount the procreation argument have filled their briefs with the words of an unlikely source: Justice Antonin Scalia, who is father to nine and grandfather to 33.
Scalia is not of the view that the Constitution protects homosexual rights, and his dissent in Lawrence v. Texas, the court's 2003 ruling that struck down that state's law outlawing sodomy, was a warning that it might lead to same-sex marriage, not an endorsement.
But a passage in the dissent speculated that procreation could not be a justification for limiting marriage to heterosexuals, "since the sterile and the elderly are allowed to marry."
The briefs also contain passionate arguments on both sides about whether same-sex marriage can be compared with interracial marriage. The latter is a subject Thomas wrote about in his autobiography.
When he met Virginia Lamp, Thomas wrote, "I had no inclination to date outside my race." She even offered to set him up with some of the black women with whom she worked. Eventually, Thomas wrote, he realized that they were soul mates and she was "a gift from God."
"How could I let my own fears, or the bigotry of others, stand in the way?" Thomas wrote in "My Grandfather's Son." "As for Virginia, she was willing to fight anybody, including friends and family, who objected to our love."
The couple settled in Virginia, whose law against interracial marriage provided the case in which the Supreme Court struck down such bans in Loving v. Virginia. The Thomases are among the 8.4 percent of American marriages with interracial partners, according to a Pew Research Center study of 2010 Census data,
All marriages, including those of the justices, have circumstances that make them special. Justice Stephen Breyer is Jewish, but was married in the Anglican Church in a ceremony tailored to couples with different religions. One daughter became an Episcopal priest; another is raising her children in the Jewish faith.
And the court's oldest justice, Ginsburg, had a prototypical "modern" marriage. She always worked and shared child-rearing with her husband Martin, who died in 2010.
Ginsburg, who turned 80 last week, has often told the story that she grew exasperated being interrupted at work by phone calls from school with complaints about her "lively" son.
"This child has two parents," she told the caller at one point. "I suggest you alternate calls."
Martin Ginsburg did all of the family's cooking - "the justice was expelled from the kitchen nearly three decades ago by her food-loving children," he once explained - and he left a lucrative New York law practice to join his wife in Washington when she was named an appeals court judge.
The justices frequently officiate at marriages, and Ginsburg told the New Yorker in a recent interview that she thinks no one has asked her or her colleagues to perform a same-sex marriage for fear they would be criticized or asked to recuse themselves from this month's cases.
Asked whether she would officiate if requested, she replied, "Why not?"