Runny nose in kittens, is it normal?

my both kittens have runny noses all the time, from day one when I brought them. my first kitten was raised all the way since he was 1 week by me, so I thought maybe he has less immunity coz he lost his mom, now my other kitten was fed by her mom for 3 months before she came to my house, she belongs to my best friend, but she also has runny nose!