What is the median?

Since the median age is less than the 2 known ages it follows that the twins are the youngest.

Let the age of the twins be x

So the ages from youngest to oldest are    x, x, 16, 19

The median age is the average ot hte two middle ages and it equals 14

so

(x+16)/2=14

x+16=28

x=28-16

x=12

The twins are 12 years old.