John,Mark and Henry Age -Math riddle


John, Mark, and Henry are three brothers. Interestingly, their current age is prime. What's more interesting is that difference between their ages is also prime. How old are they?

 

Mark is 2, John is 5, 
and Henry is 7. 

Explanation :  

Age diff,
 7 - 2 = '5' is prime; 
 7 - 5 = '2' is prime; 
 5 - 2 = '3' is prime.