Congratulations and I am sure you are one proud momma! While my Air Force basic training paled in comparison to the Marines, my parents held a fair amount of trepidation at my decision to join. In the end, the experience of serving taught me who I was. During my time in I became an adult not only in age, but in mind. The actual moment of "ascension" is still deeply ingrained in my mind, the moment I became comfortable with who I was/am as a human being, actual true acceptance.
I hope that your boys end up in as safe a division as possible, if there is such a thing in the Marines.
I will never truly understand the ascension but I've heard tales of it from all the family members who've served. They all went through that feeling of being. It's pretty amazing and I have to admit I'm a little envious. My middle son actually wrote that he felt like his body was changing. He felt stronger in mind and body. My husband is Air Force too and he even said there isn't any better training or uniform better than the Marine Corps.
Fingers crossed they stay safe but the Marine states: Rifleman first.
We were told the Marines were, "First to go, Last to know". While the "jar head" was generally a derisive type of topic among fellow airmen, really everyone looks at the Marines as "the shit". And they are!