I spent all those years in the Corp and I do not have one tattoo. My Marine brothers didn't understand why I didn't want a tat of our unit's callsign or at least my callsign on my arm. The only plausible answer I could give, "I love you all, my brothers, but my mom would wring my neck!".
To this day I don't know why. I guess, I'd hate to see what they'd look like at 40, 50, 60, etc. My grandfather has several tats on his lower arms from his tenure in the Navy during WWII and Korea. My father has a few on his arms, the most prominent is on his right bicep.