According to Bustle
"The classic dynamic of which twin is "older" will run a bit deeper for one set of Indianatwins born in different decades. That's right, with this year's progression into a new decade, New Year's twins Joslyn and Jaxon were born on two separate days, in two separate years, as a part of two separate decades. Now a few days into 2020, the twins are doing well and bonding with mom and dad."