Genes or diet??

I'm 30m, my dad and mum has normal LDL level.. and I just checked 2 weeks ago, and my LDL level is 249.

I wonder if it is possible just purely due to my extremely bad diet and exercise habit?

I mostly consume no veggie, many processed food, instant food, ramen, Hong Kong BBQ port, soy sauce chicken, and many fast food like pizza, KFC and chickfila, etc... and even worse, I almost never exercise (as I thought I was fit... (skinny fat indeed..))

I'm on the way to adjust my lifestyle, but is it possible to spike to that level purely because of lifestyle?? (my doctor said it must be genetics.)