Well-known twins Jenna Bush Hager and Barbara Bush (former President George W. Bush’s daughters) were featured in a 2015 segment on NBC’s Today Show. They discussed their deep bond from childhood and that they continue to be best friends throughout adulthood. Jenna and Barbara joked that their sense of humor is unique to them. They said few others understand it, especially Jenna’s husband Henry.

Jenna laughed, “I mean, Henry rolls his eyes at us a lot, don’t you think?”

Barbara commented, “He got me in the marriage also . . . . I think he’s had to take a number of naps with both of us and that might get annoying.”

Jenna assured Barbara that Henry really doesn’t mind: “He says he’s the ham in the ham sandwich.”

Henry’s ease with his wife’s close relationship with her twin reminded me of Eli and Gabe, identical twins I interviewed. Eli and Gabe have always been emotionally close. When they pursued graduate degrees in different cities, Eli met his wife Malka. Eli reported that what made this particular relationship work was that Malka understood the tight relationship between Eli and his brother. She was one of the only women Eli had dated who did not feel the need to compete with Gabe for Eli’s attention and affection. Malka was comfortable with, and admiring of, the close relationship between the brothers. She jokingly tells friends that Eli calls Gabe to tell him what he ate for dinner that evening.

Clearly Malka — like Henry, above — has found peace with the fact that her partner has a concurrent intimate relationship. But this isn’t typical. Studies confirm that there more often exists a mutual rivalry between spouse and co-twin. The conflict apparently arises when twins are emotionally co-dependent on one another. Twins experience difficulty with anyone who intentionally or unintentionally threatens the inter-twin attachment. Twins have an easier time bonding with partners when their relationship with their twin siblings is close but independent, as opposed to close but dependent.

Notably, though, in studies on marriage quality and twinships, twins are not more likely to divorce than singletons. And, in the event of divorce, the dissolution of marriage is more often caused by infidelity of a spouse than competition between spouse and co-twin. Such studies also demonstrate that the most harmonious marriages for twins who share a close bond are those where the twins’ respective spouses were related or friendly to each other before either one married one of the twins. This relationship that predated marriage meant there was no burden or time investment in establishing a new relationship. It meant that the twins could continue their close relationships with each other while still having successful marriages.

I have been fascinated by the study of twins and their journeys in finding and attaining intimate partnerships. It’s hard enough to find a mate when one doesn’t have the added complication of a pre-existing intimate relationship! I’ll explore more research and include more anecdotes from my interviews in subsequent posts. For now, suffice it to say that a twin’s marital partner is not simply the ham in a ham sandwich. And if he is, then we need to reframe how we see the sandwich as a whole.