I want to start by saying that when the first picture was taken I was actually in highschool, and was almost 15 years old. Despite what i am sure someone will suggest, I had already gone through puberty, trust me. But, If you were to look at every male in my family, you would see the similar genetic traits, they are all close to or over 6ft tall, and are VERY skinny. No natural muscle mass at all. I was with my sister in the first pic, and didn't want to put her pics up, so i cut her out, but what i wanted to show was not only how thin my arm was, but also how narrow my shoulders are. The distance from my neck to the edge of my shoulders looks to be only 6 inches or so, if not closer to 5. The size of my head compared to my body also references how small my body is. I had actually been training for a year at this point.
The second picture is a comparison of me between ages 16 and 21. At age 16 I had been training for about two years, and was very strict about my training and diet (had a friend who was a bodybuilder train me and set up my nutrition). The picture of me at age 21 was taken about two weeks ago. Not a great picture, the bad lighting makes it appear I have less definition than i do, but you can see the overall size difference.
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