Is atherosclerosis contagious?

No, but... Atherosclerosis is dominant human behavior in all first world countries, less so in third world countries - other physical health problems are a bigger issues there. Atherosclerosis typically starts in childhood yet typically remains asymptomatic for many decades, until plaque ruptures, clots and/or aneurysms develop. However, atherosclerosis is clearly more common in some families than others.