Last time I checked the USMC did not require tattoos. Are you suggesting that 100% of the Marines have tats all over their bodies?
95% of the US military have tattoos.
http://www.kpbs.org/news/2009/nov/09/tattooed-under-fire/
It is a military tradition, even among the officers. As I said in another post, I have never met a soldier without a tattoo and I’ve lived on military posts for more than 20 years.