The twins and sibs cited in this article lived together in the same environment and had underlying health risks.

“These deaths alert people to the fact that this could be genetic, but when people live together they share an environment as well,” Spector said. The upshot is that twins who live together are more likely to have similar lifestyles and behaviours, from diet and exercise habits to how quickly they seek medical care. Twins are not generally less healthy than the wider population. . . . “When twins or siblings tragically die with Covid-19 that captures our attention, but that doesn’t mean there’s any particular reason to think twins or siblings are at greater risk.”