Tanning

Think I’ve asked this before but still worried! My son is blonde haired and fair skinned. I live in the uk where it’s currently beautiful sunshine. I cover him in factor 50 and 5 star rated suncream. I apply before he goes out and again every hour or so. I try to keep him in the shade but he’s such an outdoor child he’s forever running around. He’s never burned where his skin is red but he does have tan lines! I feel like an awful mother because I have read articles that say tanning is bad but I don’t know what more I can do?! My husband tans really easily where I burn so I’m just wondering could he have my husband skin tone? And if there’s anything else I can do to stop him tanning?