Sibling rivalry is no new concept, but it is undoubtedly on the rise. According to The New York Times, the incidence of twin births has been on the rise since, with one in every 30 births in the US being twins, a 76 percent increase.
Sibling rivalry is no new concept, but it is undoubtedly on the rise. According to The New York Times, the incidence of twin births has been on the rise since, with one in every 30 births in the US being twins, a 76 percent increase.