Including the name of OBO in this what year were you born would be very helpful. Also, I think this needs a validation check. if it is OBO a minor, it should be <18. If it is OBO an adult or if the user is the filer, it should be 18+.
Other information
Variable being sought
users[0].birth_year
Package version
1.1.4
Maturity target
Level 4 - this is purely an enhancement to improve user experience
birth year
users[0].birth_year
1.1.4